Fady Makram Physics Mr. Singh 1st March 2009 Lab Report Aim of the experiment: The aim of this experiment was to measure the refractive index of a given glass slab, in this case a rectangular block. Apparatus: Light Box, paper, pins and a rectangular glass block. Procedure: I pinned the paper to the board using the flat head pins. I then turned on the power for the light box and placed the glass block in front of the ray of light coming from the light box. I placed a pin at the point of incidence and another on the incident ray and I then connect the pins to form both the incident ray and the point of incidence. Then I placed another two pins to form the emergent ray and the connected them with a pencil. I then joined then two rays with a straight line. I used a protractor and drew a normal, which is an imaginary line perpendicular to the glass block at the point of incidence. I measured the angle of refraction, which is the angle between the normal drawn at the point of incidence and the refractive ray. I recorded the angle of refraction which was 14 degrees. I used the same procedure to find the angle of incidence which was the angle between the normal and the incident ray. I found the angle of incidence to be 19 degrees Observations: When the ray enters the glass block, it bends towards the normal and when it exists the glass block, it bends away from the normal. This is because if a ray of light travels from a rarer to a denser material, the ray bends towards the normal and when it travels from a denser to a rarer medium, it bends away from the normal. Data Collected and Mathematical Procedure: I obtained the readings from my group and formed a table to get an average of the results. Using the mathematical formula Reflective Index = 𝐬𝐢𝐧(𝒊) I filled out a table to form 𝐬𝐢𝐧(𝒓) the results obtained from the lab. Observation # 1 2 3 4 Angle of Incidence(i) 19 27 10 15 Angle of Refraction(r) 14 19 8 13 Sin(i) Sin(r) 0.326 0.434 0.174 0.259 0.242 0.326 0.139 0.225 RI = sin(i)/sin(r) 1.346 1.294 1.248 1.151 I averaged all the refractive indexes I obtained to get the most suitable and reliable refractive index which was found to be 1.28475 Conclusion: In conclusion, we found that a ray of light passing from a rarer to a denser medium bends towards the normal and if a ray of light travels from a denser to rarer medium the ray of light bends away from the normal.