51. The sky appears blue because of
Answer: D. scattering of shorter wavelengths by air molecules
Physics Class 10 Unit 20: Electromagnetic Waves MCQs
64 multiple choice questions with the correct answer for each. Tap an option to check yourself, or switch on "Show all answers". This is page 2 of 2.
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52. The scattering of light by gas molecules is called
Answer: B. Rayleigh scattering
53. The sky appears red at sunset because
Answer: D. most of the blue light is scattered away and red light reaches us
54. Light is made of tiny massless particles called
Answer: A. photons
55. A photon has
Answer: B. energy and momentum but no mass and no charge
56. The idea that light is made of quanta was introduced by
Answer: C. Max Planck
57. The momentum of a photon is given by
Answer: B. p = h/λ
58. The momentum of a photon of frequency 4.0×1014 Hz is about
Answer: D. 8.84×10-28 kg m/s
59. Which of these EM waves has the least momentum?
Answer: A. Radio waves
60. The pressure exerted by light on objects due to transfer of momentum is called
Answer: C. radiation pressure
61. Radiation pressure is directly proportional to the
Answer: B. intensity of light
62. On halving the area of a totally reflecting surface, the radiation pressure
Answer: A. remains the same
63. A solar sail uses the
Answer: D. momentum of photons
64. Solar sails are preferred for deep-space missions because they need
Answer: C. no fuel
About Physics Class 10 Unit 20 MCQs (Federal Board)
These 64 Physics MCQs cover Class 10 Unit 20: Electromagnetic Waves of the Federal Board (FBISE) SSC-II (Class 10) syllabus. They are SLO-based MCQs as per the new pattern for FBISE exams. Each question has four options and the correct answer is shown, so you can practise for the annual examination and find the topics you still need to revise. The questions are split over 2 pages of 50. You can also read the Electromagnetic Waves notes for this chapter. Download the Electromagnetic Waves MCQs as a PDF using the button at the top of this page.