Refractive index test, Physics grades 9-10 (PDF)

Quick answer: Refraction is the bending of light as it changes speed between materials, and its size is given by the refractive index n = sin i ÷ sin r. This Physics 9-10 test on refractive index has 8 questions worth 20 marks, to do in 45 minutes: law of reflection, refractive index and bending of light. The mark scheme is on a separate page; free printable PDF.

Refractive index test with answers for GCSE physics (free PDF download)

This physics grades 9-10 test on refractive index test works like a real class test. The mark scheme is on a separate page, so revise with the lesson first.

First, this test covers reflection, refraction, critical angle and lens images. Then, show all your working and give units. So you may use a calculator and a ruler. Also, the paper is worth 20 marks.

Level: Physics grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: IGCSE 3.2

Contents

Refractive index test: the test questions

Time: 45 minutes · 8 questions · Total: 20 marks · Calculator allowed

Question 1 Law of reflection (2 marks)

First, state the law of reflection. (1 mark)
Then, a ray strikes a plane mirror at 28° to the mirror surface. Next, calculate the angle of reflection. (1 mark)

Question 2 Refractive index (3 marks)

For example, a ray in air meets a transparent plastic at an angle of incidence of 35°. Moreover, the angle of refraction is 22°. Then, calculate the refractive index. (2 marks)
Then, calculate the speed of light in the plastic. In addition, the speed of light in air is 3.0 × 10⁸ m/s. (1 mark)

Question 3 Bending of light (2 marks)

Answer both parts.

First, state whether a ray bends towards or away from the normal when it passes from air into water. (1 mark)
Then, explain why. (1 mark)

Question 4 Critical angle (3 marks)

Define critical angle. (1 mark)
Then, calculate the critical angle for a heavy glass of refractive index 1.62. (2 marks)

Question 5 Optical fibre (3 marks)

First, explain how a ray of light travels along a glass optical fibre from one end to the other. Then, include the two conditions needed. (3 marks)

Question 6 Image in a lens (4 marks)

First, the diagram shows an object in front of a converging lens, with F marking the principal focus on each side.

First, copy the diagram and draw two rays to locate the image. (2 marks)
Then, describe the image: real or virtual, upright or inverted, larger or smaller. (2 marks)

Also, F is the principal focus on each side of the lens and 2F is twice the focal length from it. Also, the sketch is not to scale.

Question 7 Magnification (2 marks)

For example, a camera forms an image 1.8 cm tall of a plant 6.0 cm tall. Calculate the magnification. (1 mark)
Then, calculate the height of the image of a 9.0 cm plant with the same setup. (1 mark)

Question 8 Real or virtual (1 mark)

Finally, state one difference between a real image and a virtual image. (1 mark)

$See the refractive index test answers and mark scheme$

State the law of reflection. — Angle of incidence equals angle of reflection (i = r).

Formula for refractive index? — n = sin i ÷ sin r

Refractive index and speed? — n = c ÷ v

What does refraction depend on? — A change in the speed of light

Ray from air into glass bends…? — Towards the normal

Formula for critical angle? — sin c = 1 ÷ n

Two conditions for total internal reflection? — Dense to less dense; angle bigger than c

Where do parallel rays meet in a converging lens? — At the principal focus F

Magnification formula? — m = image height ÷ object height

Which image can be put on a screen? — A real image