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3.2.2 Refraction of light

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Question 28

A student determines the refractive index nnn of a transparent rectangular plastic block using a ray-tracing method.

In one trial, using an angle of incidence i=40∘i = 40^\circi=40∘, the student measures the following lengths:

  • Distance along the bottom surface from the normal to the point of emergence, a=3.8 cma = 3.8\text{ cm}a=3.8 cm
  • Length of the refracted ray inside the block, b=8.5 cmb = 8.5\text{ cm}b=8.5 cm

The formula relating the refractive index nnn to these lengths for i=40∘i = 40^\circi=40∘ is:

n=0.64ba n = \frac{0.64b}{a} n=a0.64b​
a.

Calculate the value of the refractive index nnn. Give your answer to 2 or 3 significant figures.

[2]
b.

The student expected the values of refractive index obtained at different angles of incidence to be identical, but they differ slightly. State two experimental difficulties or sources of error in this type of pin-tracing experiment that could explain this difference.

[2]
c.

Which of the following is the most sensible precaution to take during this experiment to obtain highly reliable results?

  • A. View the tops of the pins.
  • B. Keep the pins as close to each other as possible.
  • C. View the bases of the pins to avoid errors due to non-vertical pins.
  • D. Perform the experiment in a completely dark room.
[1]
Markscheme

3.2.2 Refraction of light Questions

  1. IGCSE
  2. /Physics
  3. /3.2.2 Refraction of light

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.

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