# Electromagnetic waves Important Question with Answers

## Important question of electromagnetic Waves for board exam 2021

1. The speed of electromagnetic waves is independent of:
(a) wavelength
(b) frequency
(c) intensity
(d) medium in which it travels

2 Electromagnetic waves produced due to
(a) a charge at rest
(6) a moving charge
(C) an accelerating charge
(d) none of these

1. An electric charge in uniform motion produces
(a) an electric field only
(b) a magnetic field only
(C) both electric and magnetic fields
(d) no such field at all
2. Which of the following statements is a which one ? Electromagnetic waves:
(a) are produced by accelerating charges
(b) are transverse in nature
(c) travel with the same speed irrespective of the nature of the medium
(d) travel with velocity of light in vaccum

05.If E and B represent electric and magnetic vectors of the electromagnetic waves, u then direction of propagation of the electro magnetic waves is that of:
(a) E
(b) B
(c) ExB
(d) BxB

06. Among the following, longest wave is:
(b) Y-ray
(c) microwave

07.Which has the longest wavelength ?
(d) x-ray
(b) X-rays
(c) ultra-violet rays
(d) infra-red rays

08.Infra-red spectrum lies between

(b)microwave and visible region
(c)visible and ultra-violet region
(d) ultra-violet and x-ray

09.Red light differs from blue light in its:
(a)speed
(b) frequency
(c)intensity
(d) amplitude

10 Which of the following statement is wrong ?
(a) ultra-violet rays have a wavelength longer than infra-red rays
(b)infra-red rays travel with the same velocity as visible light
(c) infra-red rays can be focussed by a lens and can be reflected by a mirror just as visible light
(d) infra-red rays have more heating power than visible light rays

11.Which of the following represents an infra-red wavelength ?
(a) 104 cm
(b)10_5cm
(c)10 –6cm
(d) 10–7 cm

12. The electromagnetic waves used in the telecommunication are:
(a) ultra-violet
(b) infra-red
(c)visible
(d) microwaves

13Light beam which is highly directional, is called
(a) eraser
(b) grazer
(c) maser
(d) laser.

14.Field carried by electromagnetic wave is
(b) magnetic only
(a) electric only
(C) none of these.
(c) both (a) and (b)

15. Which of the following is shortest electromagnetic wave ?
(b) X-rays
(a) Y- rays
(C) microwaves

16.In above question which is longest electromagnetic wave?.
(a) y-rays
(b) X-rays
(c) microwaves

17 .Electromagnetic waves used in RADAR are
(b)x-rays
(a) Y-rays
(c) microwaves