Experimental skills and abilities 
Balances
A balance is used to measure the mass of an object. There are
several types available.
l In a beam balance, the unknown mass is placed in one pan
and balanced against known masses in the other pan.
l In a lever balance, a system of levers acts against the mass
when it is placed in the pan.
l A digital top-pan balance, which gives a direct reading of the
mass placed on the pan, is shown in Figure 1.
The unit of mass is the kilogram (kg). The gram (g) is
one-thousandth of a kilogram:
1
1g =
= 10−3 kg = 0.001 kg
1000 kg
Figure 1 A digital top-pan balance
How precisely do your scales measure?
l
l
A beam balance is precise to the size of the smallest mass that tilts the balanced beam.
A digital top-pan balance is precise to the size of the smallest mass which can be measured on the scale
setting you are using, probably 1 g or 0.1 g.
Rulers
Rulers are used to measure lengths. The unit of length is the metre (m). Multiples are:
l 1 decimetre (dm) = 10−1 m
l 1 centimetre (cm) = 10−2 m
l 1 millimetre (mm) = 10−3 m
l 1 micrometre (µm) = 10−6 m
A ruler is often used to measure lengths in the centimetre range. The correct way to measure with a ruler is
shown in Figure 2, with the ruler placed as close to the object as possible.
wrong
correct
70
80
ruler
object
Figure 2 Using a ruler: the reading is 76 mm or 7.6 cm. Your eye must be directly above the mark on the
scale or the thickness of the ruler causes parallax errors.
When measuring extensions (of springs, for example), it is best to record the actual scale readings for the
stretched and the unstretched lengths, and then work out the extension afterwards.
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Experimental skills and abilities
How precise are your length measurements?
It may be possible on some rulers to estimate a measurement to the nearest half-division on the scale (0.5 mm).
For very small distances, multiples can be measured and then divided to find an average (mean) value. For example,
to obtain the average thickness of one page of a book, measure the thickness of 20 pages and divide your result by 20.
Clocks and timers
Clocks, watches and timers can be used to measure time intervals. In an experiment, it is important to
choose the correct timing device for the required measurement.
The unit of time is the second (s). A stopwatch will be sufficient if a time in minutes or seconds is to
be measured, but if times of less than a second are to be determined, reaction times will influence the
measurements.
How precise are your timings?
When using a stopwatch, reaction times will influence the reading; an accuracy of about 0.5 s is the best that is
likely to be achieved. For time intervals of the order of seconds, a more precise result will be obtained by measuring
longer time intervals and then dividing to find an average (mean) value. For example, to find an average value for
the period of oscillation of a pendulum, time ten oscillations rather than one and then divide by 10.
To measure very short time intervals, use an automatic timer that can be triggered to start and stop by an
electronic signal from a microphone, photogate or mechanical switch.
Changing measurements
If values are changing rapidly, take readings more frequently. It will often be helpful to work with a partner
who watches the timer and calls out when to take a reading.
Pressing the lap-timer facility on the stopwatch at the moment you take a reading freezes the time display for
a few seconds and will enable you to record a more precise time measurement.
For rapidly changing measurements of an object’s motion, it may be necessary to use a tickertape timer
(see Experiment 1.3) or a data logger and computer.
Some other measuring devices
Measuring cylinders
meniscus
Figure 3 When taking a reading, the measuring cylinder should be vertical and your eye should be level
with the bottom of the curved liquid surface – the meniscus. (For mercury, the meniscus is curved
upwards; you should read the level of the top of the meniscus in a mercury thermometer.)
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7
Experimental skills and abilities 
The volume of a liquid can be obtained by pouring it into a measuring cylinder. The usual units for volume
are cubic metres (m3), cubic decimetres (dm3) or cubic centimetres (cm3). Measuring cylinders are often
marked in millilitres (ml) where 1 millilitre = 1 cm3; note that 1000 cm3 = 1 dm3 (= 1 litre).
The precision of the reading will depend on the size of the measuring cylinder and the spacing of the scale
marks. It may be possible to read to half a scale division if there is sufficient spacing in the marks of the scale.
Set squares
A set square is useful to determine a line at right angles to a base line. For example, in Experiment 1.4 it can
be used to check whether the ruler is at 90° to a horizontal bench. It can also be used to minimise parallax
errors by ensuring a reading is taken directly opposite a scale marking on a ruler.
2
16
17
0
1
3
15
0
14
18
19
20
21
22
0
4
13
23
1
12
24
2
11
25
3
0
26
4
05 04 03 02 01
10 20 30 40 50
The diameter of a cylinder can be found by setting it between two set squares aligned against a ruler
(see Figure 4). A set square can also be useful for drawing parallel lines.
27 28
29
Figure 4 Using two set squares to measure the diameter of a cylinder
Protractors
B
0
0
12
13
0
100 1
10
C
0
30
0
50
13
20
32°
10
0
170 180
O
20
160
10
0
0
170
12
30
180
60
15
15
70
0
160
80
90
80
40
14
°
57
90
40
50
60
70
100
14
0
A
110
D
Figure 5 Using a protractor
A protractor is used to measure angles in degrees (°).
When the angle between two intersecting lines OA and OB is required, set the horizontal (0–180°) line of
the protractor on one of the lines (OA) and the zero dot of the protractor on the intersection point of the
lines (O). The angle AOB = 57 ° can then be read off the inner scale of the protractor as shown in Figure 5.
Similarly, the angle between lines OD and OC, angle DOC = 32°, can be read from the outer scale.
The precision of the reading will depend on the size of the protractor; it is about 1° for a protractor from a
school geometry set.
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Ammeters and voltmeters
An ammeter measures electric current. The unit of current is the ampere (A). An ammeter should be placed
in series with the device in which the current is to be measured and should have a low resistance so that it
does not change the current to be measured.
A voltmeter measures potential difference (p.d.). The unit of p.d. is the volt (V). A voltmeter should be
placed in parallel with the device across which the p.d. is to be measured and should have a high resistance
so that it does not change the current and hence the p.d. to be measured.
Reading an analogue meter
4
2
6
0
8
1
2
2
3
0
10
4
1
5
volts
Figure 6 The display of an analogue voltmeter
Figure 6 shows the display of an analogue meter with two scales.
The 0–5 scale has a full-scale deflection of 5.0 V; each small-scale
division on this scale represents 0.1 V. A measurement may be able to
be made to about half a small division (here, 0.05 V). For the
0–10 scale, each small division represents 0.2 V.
As with rulers, the eye should be immediately above the pointer when
taking a reading to avoid introducing parallax errors; if there is a
mirror behind the pointer, the needle and its image should coincide
when you take a reading.
Check that the meter reads zero when there is no current; adjust the screw
at the base of the pointer until it does.
Reading a digital meter
Digital meters, such as that shown in Figure 7, allow different ranges
to be selected and the display gives the measurement in whatever
units have been chosen. The reading will be precise to the last figure
on the display, so for small currents and voltages higher precision will
be achieved by using the mA or mV setting.
Figure 7 A digital meter
Tips for using meters in electrical circuits
l
l
l
Construct circuits with the power switched off or battery disconnected and attach the voltmeter last.
Check that meters are connected with the correct polarity and are set to their largest range initially.
Set the power supply output to zero before you switch it on.
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9
Experimental skills and abilities 
Observing, measuring and recording
Having collected together and familiarised yourself with the equipment and materials needed for an
experiment, you are now ready to start making some observations and measurements.
l Decide on the range and interval of readings you will take.
l If the method does not include a diagram of the apparatus, it may be helpful at this stage to draw a clearly
labelled diagram of the experimental set-up.
l You should also record any difficulties encountered in carrying out the experiment and any precautions
taken to achieve accuracy in your measurements.
l Do not dismantle the equipment until you have completed the analysis of your results and are sure you
will not have to repeat any measurements!
l How precise will your measurements be?
l How many significant figures will your data have?
l How will you record your results?
Precision of measuring devices
Make a list of the apparatus you use in an experiment and record the smallest division of the scale of each
measuring device; since you will usually be able to take a measurement to half a small division, this will be
the precision of your measurements.
For example, the smallest division on a metre ruler is 1 mm, so the precision of any length measured with the
ruler will be about half a division (0.5 mm). The precision will be a smaller proportion of a measurement the
longer the length measured:
l For a measured length of 1 m = 1000 mm, the precision will be 1 part in 2000.
l For a measured length of 1 cm = 10 mm, the precision will be 1 part in 20.
Similarly if the divisions on a thermometer scale are at 1°C intervals, the precision of a temperature reading
will be about 0.5°C.
Significant figures
The number of digits given for a measurement or calculated value, called significant figures, indicates
how accurate we think it is. You should not give more digits in a calculated answer than are justified by the
apparatus and how it was used.
For example, a value of 6.7 has two significant figures; the value of 0.235 has three significant figures, the 2
being most significant and the 5 being the least significant.
When doing calculations your answer should have the same number of significant figures as the
measurements used in the calculation. For example, if your calculator gives an answer of 1.23578, this should
be given as 1.2 if the measurements on which you based this calculation have two significant figures and 1.24
if your measurements have three significant figures.
Note that in deciding the least significant figure you look at the following digit; if that is less than 5, you
round down (1.23 becomes 1.2) but if it is 5 or above, you round up (1.235 becomes 1.24).
If a number is expressed in standard notation, the number of significant figures is the number of digits
before the power of 10; for example, 6.24 × 102 has three significant figures.
If values with different numbers of significant figures are used to calculate a quantity, quote your answer to
the smallest number of significant figures.
Sources of error
Every measurement of a quantity is an attempt to find its true value and is subject to errors arising from the
limitations of the apparatus and the experimental procedure.
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Random errors
Limitations on the precision of a measuring device may produce random errors. If readings fall between
scale markings and have to be rounded up or down, a scatter of results occurs. Experimental difficulties such
as variable reaction times or fluctuating environmental conditions may also produce random errors.
Repeating measurements and taking the mean (see page 12) will help to average out random errors and
reduce the uncertainty in a measurement.
Systematic errors
Figure 8 shows part of a ruler used to measure the height of a point, P, above the bench.
l The ruler has a space of length x before the zero of the scale.
l The height of the point P = scale reading + x = 5.9 + x.
l By itself the scale reading is not equal to the height of P; it is too small by the amount x.
An error of this type is called a systematic error because it is introduced by the system used to make the
measurement. A half-metre ruler does not generally have a systematic error because its zero is usually at the
end of the ruler. When using a ruler to measure a height, the ruler must be held so that it is vertical. If it is at
an angle to the vertical, a systematic error will be introduced.
0
1
2
3
4
5
P
6
7
8
Before making a measurement, check to ensure that the reading is zero, otherwise a zero error must be
allowed for when a reading is taken. This can often happen with a top-pan balance or a stopwatch, for
example. See also the section on ammeters and voltmeters (page 9).
x
bench
Figure 8 Introducing a systematic error into a measurement
Tables
If several measurements of a quantity are being made, draw a table in which to record your results.
l Use the column headings, or start of rows, to name the measurement and state its unit. For example, in
Experiment 1.1 (see page 18) you will use a table similar to Table 1 to record your results.
l Repeat the measurement of each observation if possible and record the values in your table; if repeat
measurements for the same quantity are significantly different, take a third reading. Calculate an average
value from your readings. If you decide not to include an apparently anomalous value when calculating
your mean, state that it has been omitted and suggest a reason for its occurrence.
l Numerical values should be given to the number of significant figures appropriate to the measuring device.
Table 1
Mass of pendulum bob/g
First measurement of
pendulum length, L1/cm
Cambridge IGCSE™ Physics Practical Skills Workbook
Second measurement of
pendulum length, L2/cm
Average pendulum
length, L/cm
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11
ATP - Guidelines and Experimental Techniques
General Guidelines

In practical work, units and significant figures are tested. Many candidates could improve
their performance by ensuring that all numerical answers have appropriate units and are
given to an appropriate number of significant figures. Numerical values with missing or
incorrect unit results in loss of marks.

Credit is often lost due to lack of care and attention to detail when drawing or annotating
diagrams. The accuracy of straight lines on diagrams could be greatly improved by using a
sharp pencil and ruler. Drawing circuit diagrams, ray diagrams, etc without using ruler (with
free hand) results in loss of mark.

Candidates should be advised to use rulers and to attempt to mark the distance as precisely
as they can.

It is important to record measurements to the correct precision. In particular, measurements
made with a rule should be given to the nearest millimeter.
Examples:
o
If a measured length is exactly 5 cm, the value should be quoted as 5.0 cm.
o
If thermometer thread is at 22°C then write 22.0°C and not just 22°C

Candidates should be advised to avoid using rote phrases, such as, ‘to make it more
accurate’ or ‘to avoid parallax error’. These comments need to be linked to the practical
situation being considered and candidates should state why the accuracy has improved or
how parallax error was avoided.

When plotting a graph using data obtained from practical work, there will almost always be
some scatter about the line of best fit. Forcing the line through all points or always joining
the first and last points will often produce a curve/line that is not smooth.

If you are asked to “use your results” to explain something, then quote the values, do not
just mention the theory you know!

Use correct name of an apparatus otherwise your answer will not be given credit:
For Example:
o “Meter Rule” and NOT just Rule
o “Measuring Tape” or “Tape Measure” and NOT just Tape

Repeat readings to spot anomalous errors or to calculate an average

A ratio should be calculated as a decimal number, of two or three significant figures.

Candidates should be able to take readings from the graph by extrapolation or interpolation.
Control of Variables:
Control Variables should be kept constant or same to ensure a FAIR test or comparison.
For Example: When investigating effect of type of surface colour (dull and shiny) on rate of
cooling of hot water, the amount of water and initial temperature of water must be same
otherwise the comparison will not be fair.
Prepared By: Ms Urooj Fatima
Describing an Experimental Procedure
When asked to write down how to perform an experiment, your explanation should contain
following points:




List of apparatus that you will use (if not already given in the question)
How you will use this apparatus? Visualize the steps of procedure and include every
Practical Detail.
State the readings you will take and calculations involved.
In the end always mention a method to improve accuracy of the experiment. For
Example: Repeat and take average.
Recording Values in a Table:


Write both the quantity and unit in the heading. Don’t write the unit after every reading in
the table which makes it difficult to see the values clearly; a heading should say current /
ampere or just I / A
In cases where a calculated value is to be recorded in a table, the other values already
given in the table give a clue as to how many significant figures are required.

All values in a column should be given to the same number of decimal places.

Values in a column should be given to the same number of decimal places.
Variation in Raw data

When there is LARGE variation in raw data then values up to 2 decimal places are
appropriate/enough
Example:
1.19

1.00
0.93
1.03
1.08
When there is SMALL variation in raw data then the values should be given to more than 2
decimal places.
Example:
1.192
1.188
1.195
1.189
1.190
Limits of Experimental Accuracy/Error
When asked to compare two values and decide if they are constant or not; always consider the
limits of experimental accuracy/error. In Experimental data, two values even (slightly) different
are considered constant if the difference is within the Limits of Experimental Accuracy.
Usually a difference of (±10%) is considered to be within limit of experimental accuracy
If difference between values (being compared) is within (±10%) then the values are considered
to be equal/same
If difference between values is greater than (±10%) then the values are considered to be too far
apart and hence NOT equal
Writing About Human Reaction Error:
Wrong Statement: “Reduces/Minimizes human reaction error”
Right Statement: “Reduces/minimizes the EFFECT of human reaction error.”
Prepared By: Ms Urooj Fatima
Why it is better to repeat the Readings or Why it is better to take several
readings?
Wrong Statement: “Because it is more accurate or it gives more accurate reading.”
Right Statement: “Because repeating experiments gives Average and average is more
accurate.”
How to obtain a more ACCURATE reading or measurement
In ATP it is very frequently asked how you can measure a certain length or take a reading or
perform an experiment more accurately. Accuracy can be achieved by following good practices
relevant to an experimental procedure.
A few good techniques for common experimental procedures are discussed in detail in the end.
How to IMPROVE an Experiment
When asked how to improve an experiment, suggest adding/changing a procedure or method
that will improve the overall experiment in terms of reliability or ease. Do not just write about
how to make (existing) measurements more accurate.
For Example: If asked how to improve an experiment to determine time period of a pendulum,
suggest using different lengths of thread or types of bob.
Parallax Error: Error in taking measurement/reading due to position of observer
How to avoid Parallax Error:
“Line of sight should be perpendicular to the reading on apparatus” OR “view at eye-level of the
apparatus” (DON’T forget to mention the name of apparatus)
You can also draw eye position on the diagram. Candidates can be awarded credit for this even
if the explanation in words is not clear.
What is a Fiducial Aid?
A fiducial marker or fiducial is a fixed basis of reference or comparison
It is an object placed in the field of view for use as a point of reference or a measure. It may be
either something placed into or on the subject, or a mark or set of marks.
For Example: An object (such as a pencil) placed at the mean (middle) position of an oscillating
pendulum is a fiducial aid to ensure that we start and stop the stopwatch at the right time.
Break-up of Marking Criteria for Graph Plotting
Criteria
Marks
Axes: correct way round, labelled quantity and unit in correct format
(Qty/Unit)
1
Scales: more than 1/2 grid, linear, not awkward/Sensible scale (no scales of
3, 7 etc). (No discontinuity /zig-zag line in the scale)
1
Plotting: points plotted accurately within ½ small square; neat crosses or
small dots with circle around the dot. Large dots are penalized
1
Drawing: best fit straight line/Curve drawn. (Neat, thin line using sharp
pencil).
1
Prepared By: Ms Urooj Fatima
Calculating Gradient of Graph



When calculating the gradient, always use new points on the line, not your plotted points.
Draw a large triangle when measuring the gradient of a line. The hypotenuse of triangle
must be at least half the length of the line/curve. It is best to draw a triangle the full size of
the graph and to show the coordinates on the sides of the triangle when finding the gradient.
If needed, extend beyond your line beyond plotted points (only for straight line graph)
Draw a tangent to find the gradient of a curve. Make sure it is at the right place on the curve.
Again, use a large triangle
Analyzing Graphs/Relationships:

Directly Proportional Relationship:
o Graph is Linear/Straight line (constant and positive gradient) AND passes through
origin.
o When x increases, y also increases with same ratio (and vice versa). Ratio between
x and y is a constant (y = kx)

Direct - Linear Relationship:
o Graph is linear/straight line (constant and positive gradient) but DO NOT pass
through origin
o When x increases, y also increases (y = kx + c)

Direct – Non Linear Relationship:
o Graph is NOT a straight line but curve. When x increases, y also increases but nonlinearly (y ≠ kx)
o Curve with Increasing gradient  As x increases, y increases with an increasing rate
o Curve with Decreasing gradient  As x increases, y increases with a decreasing
rate.

Inversely Proportional Relationship:
o Graph is a curve (known as Hyperbola), it never passes through origin.
o When x increases, y decreases with same ratio and vice verse. Product of x and y is
a constant (xy = k )

Inverse - Linear Relationship:
o Graph is Linear/Straight line with NEGATIVE and constant gradient.
o When x increases, y decreases and vice versa. Product of x and y is NOT a
constant (xy ≠ k)

Inverse – Non Linear Relationship:
When x increases, y decreases non linearly. Product of x and y is NOT a constant
(xy ≠ k)
Prepared By: Ms Urooj Fatima
Good Experimental Techniques/Procedure
Experiments involving Measuring Techniques
Measuring Lengths:








avoid parallax in reading (ruler) / view perpendicularly
place ruler close to apparatus
check for zero error in ruler. Zero of ruler must be at the edge of ruler. If not, then the
space between edge and zero mark is called ‘Dead Space’. In case of a dead space:
o coincide the zero mark of the ruler with the object whose length is to be
measured
o measure the dead space using another ruler and add the dead space to get
corrected length/depth
clamp ruler (if applicable)
use a set square either side of a cylinder/sphere to measure diameter
use a fiducial aid when measuring a length
when measuring vertical heights ensure that the rule is held perpendicular to the base
when measuring horizontal lengths ensure that rule is held at perfect horizontal level
How to measure Vertical heights/Make sure height is Vertical
o
o
o
o
use of set-square described
use of plumb line
line up with vertical object in room
use of spirit level with explanation
How to make sure Horizontal alignment of a ruler:
o
o
o
o
measures two ends (of ruler) from the bench (same height)
use of spirit level
align with horizontal object e.g. windowsill
Use meter rule with a set square
How to measure long distances (several meters):
o
o
o
o
use Pedometer
use Trundle Wheel
measure one pace and count paces
tape measure with repeated use
How to measure length of a Pendulum accurately
o
o
o
o
measure from support to the centre of bob (place rule closer to pendulum and
avoid parallax error in reading the rule)
measure diameter of bob using micrometer and add ½ of diameter to length of
thread
measure from support to top and bottom of bob then average
vertical rule + set-square described
Measuring Time Period (of a Pendulum)
 for oscillations (of a pendulum or a vibrating object), you should be able to define a
complete oscillation
 time N oscillations, usually N>10
 Time period T is given by: T = t/N
 explain how to use a fiducial aid (a mark) at the centre of the oscillation
 Start counting oscillations from centre rather than from extreme ends because the
amplitude at extreme ends will vary in each oscillation
Prepared By: Ms Urooj Fatima
Recording time using a stopwatch

Note the precision/least count of the stopwatch and record the reading with correct
precision. If the stopwatch reads to a hundredth of a second then write complete reading for
e.g: 9.24s not just 9.0 or 9.2 and not 09:24 s

To minimize human reaction error, two persons should be used in experiments involving
recording time. (Use of some signal to start/stop stopwatch )
Recording level of liquid/water



When Meniscus is Concave shaped (for water or any other colourless liquid)  LOWER
meniscus is read.
When Meniscus is Convex shaped (for mercury)  UPPER meniscus is read.
It is better to use test tube/cylinder/beakers made of Plastic than glass because:
o Plastic is less fragile and cheaper
o Plastic gives a flat meniscus which is easier to read/ parallax error is avoided
Investigating motion of an object using a Ticker Tape
A ticker tape is a paper strip which is attached to a moving object. As the object moves, ticks
(dots) are marked on the strip at equal time interval, say every 0.20 seconds
 If the distance between dots is same, object is moving with uniform or constant speed
 If the distance between dots is increasing then object is accelerating
 If the distance between dots is decreasing then object is decelerating
Thermal/Heat Experiments
General
 cover the container
 insulate the container/provide lagging (insulating layer around the container)
 stir to ensure uniform heating
 wait for highest or steady temperature after stopping heating
 choose volume/mass values of the quantities that give large changes in the temperature
 Where water bath is required, Use oil in the bath as oil has greater resistance and hence
can provide bigger range of temperature
Thermometer handling
 thermometer in clamp stand
 thermometer with scale facing you
 clamp not obscuring the reading
 thermometer not touching the sides / bottom of test tube /
 ⅓ or ½ of thermometer immersed
 parallax avoided (in reading thermometer)
Recording TIME during heating/cooling experiments
 Place timer close to apparatus / see both (Time & Temperature) together
 two people with explanation (e.g. count down)
 parallax avoided (in reading clock)
Prepared By: Ms Urooj Fatima
Light Experiments
Ray Tracing
 use fine/sharpened pencil or draw neat thin lines
 pins far apart/at least 5 cm apart
 Pins should be vertical
 bottom of pins should be viewed
 use large angles
 repeat with different angles/vary angle of incidence
 check protractor for zero error
When using Ray Box:
 use darkened room
 use narrow slit/narrow beam/ray of light
 ray/beam strikes the mirror in the centre
Measuring Focal Length/ Using Lenses
 Ensure that each item is aligned so that the centre of each item is at the same height
and on the same horizontal straight line (ideally use the term optic axis)
o object and lens at same height (above bench)
o object and lens and screen perpendicular to bench / ruler
 place lens / screen close to ruler
 check for zero error on ruler
 Use darkened room (if an illuminated object is being used)
 move screen/object/lens backwards and forwards (until sharp image found)
 lens should be placed in lens holder
 if center of image (on screen) is above center of lens then Raise the object or screen or
lower the lens
 If center of image on screen is below center of lens then Lower the object or screen or
raise the lens
 use a fiducial aid to mark the middle of the lens on the bench/ruler
 try to use a translucent screen
Electrical Experiments
General
 check for a zero error on meter
 tap the meter to avoid sticking
 always check that connections are clean and tight
 avoid parallax in reading meters
 always check polarities (terminals connected correct way round)
 switch off the current when not making a measurement.
 use more sensitive meters
 when measuring resistance use low currents/voltages to avoid heating and changing the
resistance you are measuring
 initially choose the highest range for the ammeter/voltmeter, then reduce the range for
the ammeter so that the deflection is almost full scale
 If current is too large
o Wire overheats/melts/burn
o Damages ammeter/ammeter needle gets burnt
o Fuses melt
o Power supply trips/battery runs out quickly
Advantages of Digital Ammeter/Voltmeter over Analogue
 no parallax error
 needle does not stick
 easier to read / measure [NOT easier to use]
 easier to change range
 lower resistance
Prepared By: Ms Urooj Fatima
List of General Experiments in ATP
Measurement Techniques
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Investigating and analysing relationship between two physical quantities
Measurement of Time period of pendulum/oscillating or vibrating mass or object
Use of Measuring Instruments
o Variety of lengths using Meter rule, Tape measure, Screw Gauge, Simple callipers,
Trundle wheel etc
o Time interval using Clock/stopwatch/pendulum/laser equipment
o Use of Ticker Timer
Newtonian Mechanics
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volume and density of an irregular shaped object
investigating relationship between d-t and v-t
investigating effect of load on spring – elastic deformation
how to verify principle of moments
how to determine position of centre of mass of a piece of lamina/investigating centre of
mass of objects
Pressure in fluids
Thermal Physics
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Investigating transfer of heat energy – Conduction, Convection and Radiation
Experiments to investigate about good/bad absorbers and emitters of heat
Investigating cooling and heating
Calibration of thermometer
Use of clinical and laboratory thermometer
Use of thermocouple
Linearity/Sensitivity and range of thermometer
Calculation of specific heat capacity/latent heat
Thermal expansion
Waves
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Wave motion Transverse and longitudinal waves
Ripple tank to demonstrate Reflection and Refraction in water waves
Experiments to shoe reflection and refraction in sound waves.
Experiments to illustrate laws of reflection
Experiment to find the position and characteristics of an optical image formed by a plane
mirror.
Experiments to show refraction of light through glass blocks.
Experiments to show refraction of light through prism.
Experiments to show total internal reflection.
Experiment involving calculation of focal length by three main methods
o By two pin method
o By focusing image of an illuminated object on a screen
o By focusing image of a distant object on a screen. (rough method)
experiment to demonstrate that sound requires medium to travel – Bell Jar Experiment
experiment to measure speed of sound
Experiments to study Quality of sound waves using cro
Prepared By: Ms Urooj Fatima
Electricity and Magnetism
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Plotting of magnetic field lines with compass
Investigating strength of Electromagnet
Experiment to investigate Electrostatic force of attraction and Repulsion
Use of Ammeter and Voltmeter with different ranges
emf of batteries arranged in series/parallel
Experiment to measure the resistance of a metallic conductor using a voltmeter and an
ammeter and make the necessary calculations – Ohm’s law
Experiments to investigate relation between current, voltage, length of resistance wire,
temperature ect
Net effect of number of resisters in Series and Parallel
Series and Parallel circuits/ Potential Divider Circuits
Experiments to investigate effect of Thermistor, LDR, Diode, Capacitor
Experiment to demonstrate Thermionic emission
Use of CRO
Use of Resistor Colour Code
Atomic Physics
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Detection of alpha-particles, beta-particles and gamma-rays by appropriate methods – use
of GM tube
Prepared By: Ms Urooj Fatima
ATP - Common Experimental Procedures
Determine Diameter of a Flexible Thin Wire using given apparatus
Apparatus: Reel of thin wire, meter rule (in mm), sellotape/blu-tack, scissors
Method #1:
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Wrap the thin wire on the ruler using number of turns (N ≥10)
Find total distance x from one end to other end of the wire.
Divide x by the number of turns N to determine average value of diameter (d = x/N)
Use something to hold the wire in place on the ruler/keep wire from moving
Coils of the wire should be tight and close together
Method#2:
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Cut wire into number of pieces (N ≥10)
Line up the pieces horizontally, next to each other
Find total distance x from first piece to last
Divide x by the number of pieces N to determine average value of diameter (d = x/N)
Place the cut pieces of wire tightly closed to each other
NOTE:
 Sellotape is transparent tape used for joining, sealing, attaching, etc
 Blu-tack is an adhesive used to attach light weight objects to wall or other dry surfaces
Determine Outside Diameter of a Beaker/Cylinder/Pipe
Apparatus: string, two half meter rules, 30 cm ruler, pencil/marker pen, blocks of wood,
sellotape/blue-tac, scissors
Method #1:
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Wrap/Wound the string around the beaker several times (N ≥10)
Use something to hold the string in place on the beaker
Unwind the string and measure its total length using ruler
Divide total length of string by the number of turns N to get l (l = circumference of beaker)
Use formula l = λ d to calculate diameter of beaker d
Precautions:
 String should be wounded tightly and close together around the beaker
 Avoid parallax error in reading the ruler
Method #2:
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Place the beaker between two blocks of wood
Place the 30 cm ruler next to the wooden blocks
determine the diameter of the beaker by measuring distance on ruler between (the inner edges
of) wooden blocks
Precautions:
 Use set squares with the ruler to avoid parallax error
Prepared By: Ms Urooj Fatima
Determine Volume of an Irregular shaped object
Method #1: By using measuring cylinder
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Use of measuring cylinder stated
note initial reading
immerse object
note new reading
find difference
Method #1: By using displacement can
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use of measuring cylinder stated
fill can to spout
immerse object
find volume of water collected
Precautions
 tap cylinder to release air
 avoiding parallax in reading volume of water (read lower meniscus)
 careful pouring / avoid splashing
 repeat & average
Determine Density of an Irregular shaped solid object
Apparatus: electronic balance, graduated cylinder
Procedure:
 find volume of the object by using displacement method
 find mass of object using balance
 Calculate density using formula: d = m/v
 Repeat and take average
Determine Density of a Regular shaped solid object
Apparatus: electronic balance
Procedure:
 Calculate volume of the object by using relevant geometrical formula
 find mass of object using balance
 Calculate density using formula: d = m/v
 Repeat and take average
Measurement of Time Period (T) of a Pendulum/vibrating mass
Apparatus: Simple pendulum or vibrating mass, stop watch. Fiducial aid
Procedure:
 Release the pendulum/vibrating mass from its mean position
 measure total time, t, for a number of oscillations, N (N = 10 to 20)
 Calculate Time Period: T = t / N
 repeat readings and take average
Precautions
 count the oscillations from the centre of the swing (use fiducial aid)
 release the pendulum carefully to ensure smooth oscillations
 amplitude of swings should be small
Prepared By: Ms Urooj Fatima
Determine Centre of Mass of a Lamina
Apparatus: Lamina, plumb line, retort stand and clamp, pencil, ruler
Procedure:
 make 2/3 holes at edges of lamina
 freely suspend lamina from one hole
 use plumb-line to ensure that lamina is exactly vertical (freely suspended)
 mark vertical line on lamina (using the thread of plumb line)
 repeat from different hole(s) and find where lines meet
Precautions:
 use sharp pencil/draw neat and thin lines
 holes should be marked approx. equal distance apart and as far away as possible
 repeat from 3rd hole to check accuracy
Verify Principle of Moments
Apparatus: meter rule, retort stand (pivot), different masses with hanger
Procedure:
 first balance the meter rule on pivot without any weights/masses
 hang two sets of masses on each side and adjust their position so that the ruler is balanced
 calculate moments; clockwise moments and anticlockwise moments should be equal:
o sum of clockwise moment = sum of anticlockwise moment (hence verified)
 Repeat by using different sets of weights and changing distances
Precautions:
 Avoid parallax error in reading the rule
 Use rule with uniform width and weight
 Use smaller and equal size threads to hang weights
 Use distances from the pivot greater than 25 cm.
Verify Laws of Reflection (< i = < r)
Method #1: Using Optical Pins
Apparatus: mirror, common pins, ruler, protractor, soft board, paper, pencil
Procedure:
 Place mirror on sheet of paper
 Draw line at back of mirror on the paper
 Place 2 pins P1 and P2 on incident ray
 View pins or image (of pins) through mirror
 Place P3 and P4 in line with images of P1 and P2 to trace reflected ray
 Draw lines and normal and measure angles i and r to normal
 Repeat
Precautions:
 Pins should be placed at least 5cm apart
 Bottom of pins should be viewed to avoid parallax error
Prepared By: Ms Urooj Fatima
Method #2: Using Ray- box
Apparatus: mirror, ray-box, ruler, protractor, soft board, paper, pencil
Procedure:
 Place mirror on sheet of white paper and draw line at back of mirror on the paper
 Place ray-box in front of the paper so that light ray can be seen on the paper
 By using ray box, direct a ray of light (incident ray) at some angle to the plane mirror.
 Trace incident ray and reflected ray on paper (mark two points for each ray and then draw
straight lines with ruler)
 Draw normal and measure angles i and r to normal
 Repeat by directing ray of light at different angles
Precautions:
 Thin ray of light should be used
 Use darkened room
Refraction of Light/Find Refractive Index
Method #1: Using Optical Pins
Apparatus: Glass block, common pins, ruler, protractor, board, paper, pencil
Procedure:
 Place glass block on sheet of white paper and draw its Outline on paper
 Place 2 pins on incident ray
 View pins through glass block from other side
 place P3 and P4 in line with P1 and P2 to trace emergent ray
 Join points to get incident ray and emergent ray (in air), remove block and draw ray inside
block to get Refracted ray
 Draw Normal, measure Angle of incidence and angle of refraction.
 Calculate Refractive Index using formula : μ = sin i /sin r
 repeat
Method #2: Using Ray-box
Apparatus: Glass block, ray-box, ruler, protractor, board, paper, pencil
Procedure:
 Place glass block on sheet of white paper and draw its Outline on paper
 Place ray-box in front of the paper so that light ray can be seen on the paper
 By using ray box, direct a ray of light (incident ray) at some angle to the glass block
 Trace incident ray and emergent ray on paper (mark two points for each ray and then draw
straight lines with ruler)
 Remove the block and draw Refracted ray inside block by joining the point where ray
entered the block to the point where it emerged out of the block.
 Draw Normal, measure Angle of incidence and angle of refraction.
 Calculate Refractive Index using formula : μ = sin i /sin r
 repeat
Prepared By: Ms Urooj Fatima
Total Internal Reflection/measure Critical angle
Apparatus: semicircular glass block, ray-box, ruler, protractor, board, paper, pencil
Procedure:
 Place semicircular glass block on sheet of white paper and draw its Outline on paper
 Place ray-box in front of the paper so that light ray can be seen on the paper
 Using ray-box, direct a ray of light (incident ray) to enter the semicircular block from its
curved edge towards its centre
 Gradually increases angle of incidence until refracted ray runs along surface
 At this point, trace incident ray.
 Draw normal, measure angle of incidence. < i = < c (angle of incidence = critical angle)
 Further increase < i , TIR is observed. (ray of light will not emerge out of the semicircular
block from other side but will be reflected back)
Determine Focal length of lens – Rough method
Apparatus: converging lens, distant object/source of light, screen, meter rule/optical bench
Procedure:
 use light from a distant object (or light from sun)
 move lens or screen until a focused image is obtained on the screen
 measure distance from lens to screen
 repeat and average
Focal length of lens – accurate method
Apparatus: converging lens, illuminated object, screen, meter rule
Procedure:
 place lens at centre of meter rule
 place object and screen on either side of lens
 move object or screen until a focused image is obtained on the screen
 measure object distance (u) and image distance (v)
 use formula to calculate focal length : f = (u x v) ÷ (u + v)
 repeat by changing object/image distances
Precautions:
 use darkened room
 align centres of object, lens and screen
 avoid parallax error in reading meter rule
Plotting Magnetic Field lines of a Bar magnet using plotting compass
Apparatus: bar magnet, plotting compass, paper, pencil
Procedure:
 Place plotting compass near magnet
 Mark the position of end of compass needle with a dot
 move the compass to point to previous dot, mark new dot (along one field line)
 repeat until the S-pole of the bar magnet is reached
 join dots to give filed line
 Repeat with different starting points to get more filed lines
Prepared By: Ms Urooj Fatima
Precautions:
 There should not be any other magnet or magnetic material present nearby the apparatus
 Use smaller plotting compass (gives more dots)
 Avoid parallax error in marking the dots
Measure Resistance of an unknown Resistor/Verify Ohm’s Law
Apparatus: Ammeter, voltmeter, fixed resistor of unknown value, Rheostat/variable resistor (or
any means of varying current in circuit), battery/power supply, connecting leads,
Procedure:
 Set up circuit containing power supply, resistor, ammeter in series, voltmeter across resistor
and some means of varying current (e.g. variable resistor, variable power supply, change/add
cells)
 Adjust the variable resistor so that a suitable value of voltage and current is obtained. Record
V and I
 Take several reading of V and I (by changing current in the circuit)
 Use V = IR and calculate average R or plot I–V graph and find R
Precautions:
 Avoid parallax error in reading ammeter/voltmeter
 Switch off current after each reading to avoid overheating
 Use smaller values of current
 All electrical connections should be tight and rust free
To Investigate effect of Temperature on Resistance
Apparatus: Ammeter, voltmeter, resistor, water/oil bath, battery/power supply, connecting leads,
Procedure:
 Set up circuit containing Resistor (immersed in water/oil bath), power supply, ammeter in
series, voltmeter in parallel with resistor
 Heat water bath to change temperature
 Use thermometer above resistor to record temperatures
 Record values of Current and Voltage at different values of Temperature,
 Calculate R (R = V/I)
Precautions:
 Thermometer should be placed close to resistor (even in air)
 Stir water / allow to settle
 Avoid parallax error in reading ammeter/voltmeter
 Reduce draughts in the room/lab
 Use wooden/plastic stirrer to avoid short circuit
Prepared By: Ms Urooj Fatima
To Investigate how Resistance of a wire/conductor depends on its Length
Apparatus: Test Wire/Conductor, ammeter, voltmeter, fixed resistor, battery/power supply,
connecting leads, movable lead
Procedure:
 Set up circuit containing fixed Resistor, wire under test, power supply and ammeter in series,
and voltmeter in parallel with wire under test
 Change length of wire by connecting the movable lead at different lengths along the wire
 Record values of Current and Voltage at different values of length
 Calculate R (for each length)
(R = V/I)
Precautions:
 Avoid parallax error in reading ammeter/voltmeter
 Use smaller values of current
 Switch off the circuit after taking each reading
 Use water bath to keep the temperature constant
Prepared By: Ms Urooj Fatima