Bihar Board - Class 12 Physics - Chapter 8: Electromagnetic Waves Multiple Choice Questions (MCQs)
For Class 12 Bihar Board, the chapter Electromagnetic Waves in Physics explain the nature, properties, and spectrum of electromagnetic waves, along with their production and applications. You can find multiple-choice questions that help in mastering these topics and preparing effectively for exams on Vidyakul.
Multiple Choice Question
1. Displacement current goes through the gap between the plates of a capacitor when the charge on the capacitor
(A) is changing with time
(B) decreases
(C) does not change
(D) decreases to zero
Answer: (A) is changing with time
2. Ampere's circuital law holds good for
(A) conduction current
(B) displacement current
(C) Both (A) and (B)
(D) None of these
Answer: (C) Both (A) and (B)
3. An electron oscillating with a frequency of 3 x 10 Hz, would generate
(A) X-rays
(B) ultraviolet rays
(C) radio waves
(D) microwaves
Answer: (C) radio waves
4. Which of the following has zero average value in a plane electromagnetic wave?
(A) Both magnetic and electric field
(B) Electric field only
(C) Magnetic energy
(D) Electric energy
Answer: (A) Both magnetic and electric field
5. In an electromagnetic wave, the electric and magnetic fields are 100 V m-1 and 0. 265 A m-1. The maximum energy flow is
(A) 26. 5 W/m²
(B) 36.5 W/m²
(C) 46. 7 W/m²
(D) 765 W/m²
Answer: (A) 26. 5 W/m²
6. According to Maxwell's hypothesis, a changing electric field gives rise to
(A) an e. m. f
(B) electric displacement current
(C) magnetic field
(D) pressure gradient
Answer: (C) magnetic field
7. Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor?
(A) is changing with time
(B) decreases
(C) increases
(D) Both 2 and 3
Answer: (D) Both 2 and 3
8. When electromagnetic waves enter the ionized layer of ionosphere, then the relative permittivity i. e. dielectric constant of the ionized layer
(A) does not change
(B) appears to increase
(C) appears to decrease
(D) sometimes appears to increase and sometimes to decrease
Answer: (C) appears to decrease
9. Which one of the following has the maximum energy?
(A) Radio waves
(B) Infrared rays
(C) Ultraviolet rays
(D) Microwaves
Answer: (C) Ultraviolet rays
10. The oscillating electric and magnetic vectors of an electromagnetic wave are oriented along
(A) the same direction but differ in phase by 90°
(B) the same direction and are in phase
(C) mutually perpendicular directions and are in phase
(D) mutually perpendicular directions and differ in phase by 90°
Answer: (C) mutually perpendicular directions and are in phase
11. Displacement current is
(A) continuous when electric field is changing in the circuit
(B) continuous when magnetic field is changing in the circuit
(C) continuous in both types of fields
(D) continuous through wires and resistance only
Answer: (A) continuous when electric field is changing in the circuit
12. Select the wrong statement. EM waves
(A) are transverse in nature.
(B) travel in free space at the speed of light.
(C) are produced by accelerating charges.
(D) travel in all media with the same speed.
Answer: (D) travel in all media with the same speed.
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