JEE Main Electromagnetic Waves Practice Questions With Solutions

Updated By Diksha Sharma on 07 Jan, 2025 21:16

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JEE Main Physics Electromagnetic Waves Practice Questions

Chemistry Mathematics

Question 1.

The magnetic field in a plane electromagnetic wave is $B_{y} = (3.5 \times 10^{- 7}) \sin (1.5 \times 10^{3} x + 0.5 \times 10^{11} t) T$ . The corresponding electric field will be :

E_{z} = 105 \sin (1.5 \times 10^{3} x + 0.5 \times 10^{11} t) {Vm}^{- 1}

E_{y} = 10.5 \sin (1.5 \times 10^{3} x + 0.5 \times 10^{11} t) {Vm}^{- 1}

E_{y} = 1.17 \sin (1.5 \times 10^{3} x + 0.5 \times 10^{11} t) {Vm}^{- 1}

E_{z} = 1.17 \sin (1.5 \times 10^{3} x + 0.5 \times 10^{11} t) {Vm}^{- 1}

Question 2.

A plane EM wave is propagating along $x$ direction. It has a wavelength of $4 mm$ . If electric field is in $y$ direction with the maximum magnitude of $60 {Vm}^{- 1}$ , the equation for magnetic field is :

B_{z} = 2 \times 10^{- 7} \sin [\frac{π}{2} (x - 3 \times 10^{8} t)] \hat{k} T

B_{z} = 2 \times 10^{- 7} \sin [\frac{π}{2} \times 10^{3} (x - 3 \times 10^{8} t)] \hat{k} T

B_{z} = 60 \sin [\frac{π}{2} (x - 3 \times 10^{8} t)] \hat{k} T

B_{x} = 60 \sin [\frac{π}{2} (x - 3 \times 10^{8} t)] \hat{i} T

Question 3.

Average force exerted on a non-reflecting surface at normal incidence is $2.4 \times 10^{- 4} N$ . If $360 W / {cm}^{2}$ is the light energy flux during span of 1 hour 30 minutes, Then the area of the surface is:

20 m^{2}

0.2 m^{2}

0.1 m^{2}

0.02 m^{2}

Question 4.

In the given electromagnetic wave $E_{y} = 600 \sin (ω t - kx) {Vm}^{- 1}$ , intensity of the associated light beam is (in $W / m^{2}$ : (Given $ϵ_{0} = 9 \times 10^{- 12} C^{2} N^{- 1} m^{- 2}$ )

486

729

243

972

Question 5.

Electromagnetic waves travel in a medium with speed of $1.5 \times 10^{8} m s^{- 1}$ . The relative permeability of the medium is 2.0. The relative permittivity will be:

Question 6.

Match List I with List II :

	LIST I EM-Wave		LIST II Wavelength Range
A.	Infra-red	I.	$< 10^{- 3}$ nm
B.	Ultraviolet	II.	400 nm to 1 nm
C.	X-rays	III.	1 mm to 700 nm
D.	Gamma rays	IV.	1 nm to $10^{- 3}$ nm

Choose the correct answer from the options given below :

(A)-(I), (B)-(III), (C)-(II), (D)-(IV)

(A)-(III), (B)-(II), (C)-(IV), (D)-(I)

(A)-(IV), (B)-(III), (C)-(II), (D)-(I)

(A)-(II), (B)-(I), (C)-(IV), (D)-(III)

Question 7.

Arrange the following in the ascending order of wavelength:

A. Gamma rays $(λ_{1})$

B. $x$ - rays $(λ_{2})$

C. Infrared waves $(λ_{3})$

D. Microwaves $(λ_{4})$

Choose the most appropriate answer from the options given below

λ_{1} < λ_{2} < λ_{3} < λ_{4}

λ_{2} < λ_{1} < λ_{4} < λ_{3}

λ_{4} < λ_{3} < λ_{2} < λ_{1}

λ_{4} < λ_{3} < λ_{1} < λ_{2}

Question 8.

The electric field in an electromagnetic wave is given by $\vec{E} = \hat{i} 40 \cos ω (t - z / c) {NC}^{- 1}$ . The magnetic field induction of this wave is (in SI unit) :

\vec{B} = \hat{j} \frac{40}{c} \cos ω (t - z / c)

\vec{B} = \hat{i} \frac{40}{c} \cos ω (t - z / c)

\vec{B} = \hat{j} 40 \cos ω (t - z / c)

\vec{B} = \hat{k} \frac{40}{c} \cos ω (t - z / c)

Question 9.

If frequency of electromagnetic wave is

60 MHz

and it travels in air along

z

direction then the corresponding electric and magnetic field vectors will be mutually perpendicular to each other and the wavelength of the wave (in

m

) is :

2.5

Question 10.

Given below are two statements:

Statement I: Electromagnetic waves carry energy as they travel through space and this energy is equally shared by the electric and magnetic fields.

Statement II: When electromagnetic waves strike a surface, a pressure is exerted on the surface.

In the light of the above statements, choose the most appropriate answer from the options given below:

Statement I is incorrect but Statement II is correct.

Both Statement I and Statement II are correct.

Statement I is correct but Statement II is incorrect.

Both Statement I and Statement II are incorrect.

Question 1.

In a plane EM wave, the electric field oscillates sinusoidally at a frequency of $5 \times 10^{10} Hz$ and an amplitude of $50 {Vm}^{- 1}$ . The total average energy density of the electromagnetic field of the wave is : [Use $ε_{0} = 8.85 \times 10^{- 12} C^{2} / {Nm}^{2}$ ]

4.425 \times 10^{- 8} {Jm}^{- 3}

2.212 \times 10^{- 10} {Jm}^{- 3}

2.212 \times 10^{- 8} {Jm}^{- 3}

1.106 \times 10^{- 8} {Jm}^{- 3}

Question 2.

The electric field of an electromagnetic wave in free space is represented as $\vec{E} = E_{0} \cos (ω t - kz) \hat{i}$ . The corresponding magnetic induction vector will be :

\vec{B} = E_{0} C \cos (ω t + k z) \hat{j}

\vec{B} = \frac{E_{0}}{C} \cos (ω t - kz) \hat{j}

\vec{B} = E_{0} C \cos (ω t - k z) \hat{j}

\vec{B} = \frac{E_{0}}{C} \cos (ω t + kz) \hat{j}

Question 3.

A plane electromagnetic wave of frequency $35 MHz$ travels in free space along the $X$ -direction. At a particular point (in space and time) $\vec{E} = 9.6 \hat{j} V / m$ . The value of magnetic field at this point is :

9.6 \hat{j} T

3.2 \times 10^{- 8} \hat{i} T

9.6 \times 10^{- 8} \hat{k} T

3.2 \times 10^{- 8} \hat{k} T

Question 4.

An object is placed in a medium of refractive index 3 . An electromagnetic wave of intensity $6 \times 10^{8} W / m^{2}$ falls normally on the object and it is absorbed completely. The radiation pressure on the object would be (speed of light in free space $= 3 \times 10^{8} m / s$ ) :

6 {Nm}^{- 2}

36 {Nm}^{- 2}

18 {Nm}^{- 2}

2 {Nm}^{- 2}

Question 5.

A plane electromagnetic wave propagating in $x$ -direction is described by

$E_{y} = (200 {Vm}^{- 1}) \sin [1.5 \times 10^{7} t - 0.05 x];$

The intensity of the wave is :

(Use $ϵ_{0} = 8.85 \times 10^{- 12} C^{2} N^{- 1} m^{- 2}$ )

35.4 {Wm}^{- 2}

53.1 {Wm}^{- 2}

26.6 {Wm}^{- 2}

106.2 {Wm}^{- 2}

Question 6.

Match List I with List II of Electromagnetic waves with corresponding wavelength range :

List I	List II
(A) Microwave	(I) $400 nm$ to $1 nm$
(B) Ultraviolet	(II) $1 nm$ to $10^{- 3} nm$
(C) X-Ray	(III) $1 mm$ to $700 nm$
(D) Infra-red	(IV) $0.1 m$ to $1 mm$

Choose the correct answer from the options given below:

(A)-(I), (B)-(IV), (C)-(II), (D)-(III)

(A)-(IV), (B)-(I), (C)-(II), (D)-(III)

(A)-(IV), (B)-(I), (C)-(III), (D) -(II)

(A)-(IV), (B)-(II), (C)-(I), (D)-(III)

Question 7.

In an electromagnetic wave, at an instant and at particular position, the electric field is along the negative $z$ -axis and magnetic field is along the positive $x$ -axis. Then the direction of propagation of electromagnetic wave is:

45^{\circ}

angle from positive y-axis

positive

y

-axis

negative

y

-axis

positive z-axis

Question 8.

Which of the following Maxwell's equation is valid for time varying conditions but not valid for static conditions :

\oint \vec{E} \cdot \vec{d l} = 0

\oint \vec{B} \cdot \vec{d l} = μ_{0} I

\oint \vec{E} \cdot \vec{d l} = - \frac{\partial ϕ_{B}}{\partial t}

\oint \vec{D} \cdot \vec{d A} = Q

Question 9.

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$

Assertion A : EM waves used for optical communication have longer wavelengths than that of microwave, employed in Radar technology.

Reason R : Infrared EM waves are more energetic than microwaves, (used in Radar)

In the light of given statements, choose the correct answer from the options given below.

Both

A

and

R

are true but

R

is NOT the correct explanation of

A

A

is true but

R

is false

Both

A

and

R

are true and

r

is the correct explanation of

A

A

is false but

R

is true

Question 10.

A plane electromagnetic wave of frequency $20 MHz$ propagates in free space along $x$ -direction. At a particular space and time, $\vec{E} = 6.6 \hat{j} V / m$ . What is $\vec{B}$ at this point?

- 2.2 \times 10^{- 8} \hat{i} T

2.2 \times 10^{- 8} \hat{i} T

2.2 \times 10^{- 8} \hat{k} T

- 2.2 \times 10^{- 8} \hat{k} T

JEE Main Electromagnetic Waves Practice Questions With Solutions

JEE Main Physics Electromagnetic Waves Practice Questions

Question 1.

Question 2.

Question 3.

Question 4.

Question 5.

Question 6.

Question 7.

Question 8.

Question 9.

Question 10.

Question 1.

Question 2.

Question 3.

Question 4.

Question 5.

Question 6.

Question 7.

Question 8.

Question 9.

Question 10.

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