IGCSE - Physics - MCQ 12 - Light Waves [PDF]

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Chapter 12 1 Which of the following is the reason why we see objects? A They reflect light. B They refract light. C They all emit their own light. D They are fluorescing.



2 Which of the following is a property of waves? A reflection B refraction C diffraction D all of the above



3 Complete the sentence: The angle of incidence is A equal to the angle of reflection. B greater than the angle of reflection. C less than the angle of reflection. D not comparable to the angle of reflection.



4 Which of the following objects uses mirrors and the law of reflection in order to work? A a periscope B an endoscope C a kaleidoscope D all of the above



5 Complete the sentence: Refraction causes light to A bounce off surfaces.



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B pass through substances with no effect. C change speed. D bend around corners.



6 What happens when a ray of light goes from a less dense medium into a more dense medium? A It bends towards the normal. B It bends away from the normal. C It passes straight through the medium with no change. D It reflects back at the boundary.



7 Which of the following best describes the term refractive index? A the number that represents the amount a substance bends light B the number that represents the amount a light ray is reflected C the angle through which light bends D none of the above



8 A ray of light in air enters a glass block. The angle of incidence in air is 30°. The angle of refraction is 20°. What is the refractive index of the glass? A 1.00 B 0.68 C 1.46 D 0.17



9 The refractive index of glass is 1.33. If the angle of incidence is 45°. What is the angle of refraction? A 45° B 32° C 53° D 50°



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10 Total internal reflection occurs under which conditions? A when the angle of incidence is greater than the critical angle B when the angle of incidence is smaller than the critical angle C when the angle of reflection is greater than the critical angle D when the angle of reflection is smaller than the critical angle



11 What is the critical angle for glass when the refractive index is 1.45? A 52⁰ B 42⁰ C 44⁰ D 34⁰



12 Which of the following statements is a reason for using prisms over plane mirrors in a periscope? A The picture will be in colour. B The light is refracted rather than refracted. C The image will be brighter and clearer. D the image will be the same.



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Answers 1



A – Those objects that emit their own light can be seen easily but all objects do not emit light. All objects will reflect light which is why they can be seen. 2 D – All transverse waves have all three of the properties. 3 A 4 D – All use mirrors or prisms which reflect light according to the law of reflection. 5 C – Travelling into a more dense medium slows the wave down whereas travelling into a less dense medium speeds it up. 6 A – The slowing of the wave causes it to bend towards the normal. 7 A 8 C 9 B 10 A – A little total internal reflection (TIR) will occur as the light approaches the critical angle but when the angle of incidence is greater than the critical angle all light will TIR. 11 C 12 C



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