Electromagnetic Waves MCQ Questions & Answers in Electrostatics and Magnetism | Physics

Learn Electromagnetic Waves MCQ questions & answers in Electrostatics and Magnetism are available for students perparing for IIT-JEE, NEET, Engineering and Medical Enternace exam.

1. Which of the following statements is true?

A The wavelength of microwaves is greater than that of UV-rays
B The wavelength of IR rays is lesser than that of UV-rays
C The wavelength of microwaves is lesser than that of IR rays
D Gamma rays has largest wavelength in the electromagnetic spectrum.
Answer :   Gamma rays has largest wavelength in the electromagnetic spectrum.

2. The velocity of electromagnetic radiation in a medium of permittivity $${\varepsilon _0}$$ and permeability $${\mu _0}$$ is given by

A $$\sqrt {\frac{{{\varepsilon _0}}}{{{\mu _0}}}} $$
B $$\sqrt {{\mu _0}{\varepsilon _0}} $$
C $$\frac{1}{{\sqrt {{\mu _0}{\varepsilon _0}} }}$$
D $$\sqrt {\frac{{{\mu _0}}}{{{\varepsilon _0}}}} $$
Answer :   $$\frac{1}{{\sqrt {{\mu _0}{\varepsilon _0}} }}$$

3. In an apparatus, the electric field was found to oscillate with an amplitude of $$24\,V/m.$$  The magnitude of the oscillating magnetic field will be

A $$6 \times {10^{ - 6}}T$$
B $$2 \times {10^{ - 8}}T$$
C $$8 \times {10^{ - 8}}T$$
D $$12 \times {10^{ - 6}}T$$
Answer :   $$8 \times {10^{ - 8}}T$$

4. Given below is a list of electromagnetic spectrum and its mode of production. Which one does not match?

A Gamma rays - Radioactive decay of the nucleus
B Ultraviolet rays - Magnetron valve
C Radio wave - Rapid acceleration and deceleration of electrons in conducting wires
D X-rays - coolidge tube
Answer :   X-rays - coolidge tube

5. Which of the following has/have zero average value in a plane electromagnetic wave?

A Both magnetic and electric fields
B Electric field only
C Magnetic field only
D Magnetic energy
Answer :   Both magnetic and electric fields

6. In an apparatus, the electric field was found to oscillate with an amplitude of $$18\,V/m.$$  The magnitude of the oscillating magnetic field will be

A $$4 \times {10^{ - 6}}T$$
B $$6 \times {10^{ - 8}}T$$
C $$9 \times {10^{ - 9}}T$$
D $$11 \times {10^{ - 11}}T$$
Answer :   $$6 \times {10^{ - 8}}T$$

7. In a plane electromagnetic wave propagating in space has an electric field of amplitude $$9 \times {10^3}\,V/m,$$   then the amplitude of the magnetic field is

A $$2.7 \times {10^{12}}T$$
B $$9.0 \times {10^{ - 3}}T$$
C $$3.0 \times {10^{ - 4}}T$$
D $$3.0 \times {10^{ - 5}}T$$
Answer :   $$3.0 \times {10^{ - 5}}T$$

8. If $${\lambda _v},{\lambda _x}$$  and $${\lambda _m}$$ represent the wavelengths of visible light, X-rays and microwaves respectively, then

A $${\lambda _m} > {\lambda _x} > {\lambda _v}$$
B $${\lambda _v} > {\lambda _m} > {\lambda _x}$$
C $${\lambda _m} > {\lambda _v} > {\lambda _x}$$
D $${\lambda _v} > {\lambda _x} > {\lambda _m}$$
Answer :   $${\lambda _m} > {\lambda _v} > {\lambda _x}$$

9. Which of the following is the correct equation for magnetic field as a function of $$x,$$ and $$t$$ where a plane electromagnetic wave propagating in the $$x$$-direction has a wavelength of $$5.0\,mm$$  ? The electric field is in the $$y$$-direction and its maximum value is $$30\,V{m^{ - 1}}.$$

A $$B = {10^{ - 3}}\sin \left[ {\frac{{2\pi }}{{5 \times {{10}^{ - 3}}}}\left( {ct - x} \right)} \right]$$
B $$B = {10^{ - 7}}\sin \left[ {\frac{{2\pi }}{{5 \times {{10}^{ - 3}}}}\left( {ct - x} \right)} \right]$$
C $$B = {10^{ - 5}}\sin \left[ {\frac{\pi }{{1.5 \times {{10}^{ - 3}}}}\left( {ct - x} \right)} \right]$$
D None of these
Answer :   $$B = {10^{ - 7}}\sin \left[ {\frac{{2\pi }}{{5 \times {{10}^{ - 3}}}}\left( {ct - x} \right)} \right]$$

10. Which of the following waves have the maximum wavelength

A X-rays
B I.R. rays
C UV rays
D Radio waves
Answer :   Radio waves