A student is investigating the refraction of light passing through a rectangular block of transparent material. The student first draws the outline of the block ABCD ABCD\,ABCD on a ray-trace sheet. They draw a normal to the side AB AB\,AB at point EEE, then draw an incident line FE FE\,FE at an angle of incidence i1=35∘i_1 = 35^\circi1=35∘ to the normal.
The student places two pins, P1 P_1\,P1 and P2P_2P2, on the line FEFEFE. Explain why the pins P1 P_1\,P1 and P2 P_2\,P2 should be placed as far apart as possible (at least 5.0 cm apart).
The student views the pins through the opposite face, CDCDCD, and places pins P3 P_3\,P3 and P4 P_4\,P4 so they align with the images of P1 P_1\,P1 and P2P_2P2. They then draw the refracted ray inside the block, GEGEGE. The student measures the angle of refraction r1 r_1\,r1 between the line GE GE\,GE and the normal as r1=23∘r_1 = 23^\circr1=23∘. (i) Calculate the ratio i1r1\displaystyle \frac{i_1}{r_1}r1i1 for this trial. Give your answer to 2 or 3 significant figures and without any unit.
The student repeats the procedure with an angle of incidence i2=50∘i_2 = 50^\circi2=50∘ and measures the new angle of refraction as r2=32∘r_2 = 32^\circr2=32∘. (i) Calculate the ratio i2r2\displaystyle \frac{i_2}{r_2}r2i2 for this trial. Give your answer to 2 or 3 significant figures and without any unit.
A classmate suggests that the ratio of the angles ir\displaystyle \frac{i}{r}ri should be a constant. State and explain briefly whether your results in (b)(i) and (c)(i) support this suggestion.
100 exam-style questions on CIE IGCSE Physics 3.2.2 Refraction of light. Each one has a worked solution and a mark scheme showing where the marks go.