Class 12th Physics Chapter 8 Electro-Magnetic Waves VVI Objective Question

Electro-Magnetic Waves

1. Which has the longest wavelength?

(B) X-rays

(C) Ultraviolet rays

(D) Infrared

2. Which of the following has a minimum wavelength?

(A) X-Rays

(B) Y-Rays

(C) Micro Wave

3. The frequency range of microwaves (in hertz) is

(A) 3 × 108 – 4 x 104

(B) 7.5 x 104 – 3.8 x 1011

(C) 3 x 1021 – 3 x 1018

(D) 3 x 1012 – 3 x 1010

4. Wavelength range in meter for green light is

(A) 4x 10-7– 4.5 x 10-7

(B) 4.5 x 10-7 – 5 x 10-7

(C) 5 x 10-7 – 5.7 x 10-7

(D) None of these

5. According to the law of electromagnetism, the speed of electromagnetism in all the inertial frames is

(A) Same

(B) different

(C) not definite

(D) None of these.

6. Maxwell equations represent four laws of electromagnetism. Maxwell Ampere law relates

(A) The rate of change of magnetic flux to total current

(B) The rate of change of magnetic flux to displacement current

(C) the rate of change of magnetic flux to current

(D) None of these

7. Unit of displacement current is

(A) A

(B) AM

(C) OmA

(D) I

8. Which of the following are used to make labs free from bacteria?

(A) U-V rays

(B) I-R rays

(C) X-rays

(D) none

9. The propagation of the electromagnetic wave is along

(A) normal to electric field only

(B) normal to magnetic field only

(C) normal to both the electric, and magnetic field

(D) None of these

10. Which is a wrong statement?

(A) Electromagnetic waves are transverse

(B) Electromagnetic waves travel in a vacuum at the speed of light

(C) The speed of the electromagnetic wave is the same in all media

(D) Electromagnetic waves are emitted by accelerated charges

11. The water molecule in foods have a rotational frequency in the range of

(A) ultraviolet waves

(B) infrared waves

(C) microwaves

(D) visible waves

12. The frequency of the microwave is

(A) less than that of radiowaves

(B) more than that of radiowaves para

(C) more than that of light waves

(D) less than the range of audible waves

13. Which of the following is not shown by electromagnetic waves?

(A) reflection

(B) polarization

(C) diffraction

(D) None of these

14. The energy of electromagnetic radiation is 13.2 keV. This radiation is related to which region of the spectrum ?

(A) Visible

(B) X-rays

(C) Ultra violet

(D) Infrared