JEE Main 2015 (Online) 10th April Morning Slot | Electromagnetic Waves Question 7 | Physics

JEE Main 2015 (Online) 10th April Morning Slot

MCQ (Single Correct Answer)

-1

An electromagnetic wave travelling in the x-direction has frequency of 23 $$ \times $$ 10¹⁴ Hz and electric field amplitude of 27 Vm^$$-$$1. From the options given below, which one describes the magnetic field for this wave ?

$$\overrightarrow B $$ (x, t) = (3 $$ \times $$ 10^$$-$$8T) $$\widehat j$$

sin [ 2$$\pi $$ (1.5 $$ \times $$ 10^$$-$$8x $$-$$ 2 $$ \times $$ 10¹⁴t)]

$$\overrightarrow B $$ (x, t) = (9 $$ \times $$ 10^$$-$$8T) $$\widehat k$$

sin [ 2$$\pi $$ (1.5 $$ \times $$ 10^$$-$$6x $$-$$ 2 $$ \times $$ 10¹⁴t)]

$$\overrightarrow B $$ (x, t) = (9 $$ \times $$ 10^$$-$$8T) $$\widehat i$$

sin [ 2$$\pi $$ (1.5 $$ \times $$ 10^$$-$$8x $$-$$ 2 $$ \times $$ 10¹⁴t)]

$$\overrightarrow B $$ (x, t) = (9 $$ \times $$ 10^$$-$$8T) $$\widehat j$$

sin [(1.5 $$ \times $$ 10^$$-$$6 x $$-$$ 2 $$ \times $$ 10¹⁴t)]

JEE Main 2025 (Online) 29th January Evening Shift

MCQ (Single Correct Answer)

-1

A plane electromagnetic wave propagates along the + x direction in free space. The components of the electric field, $\vec{E}$ and magnetic field, $\vec{B}$ vectors associated with the wave in Cartesian frame are

$E_x, B_y$

$E_y, B_x$

$E_y, B_z$

$E_z, B_y$

JEE Main 2025 (Online) 29th January Morning Shift

MCQ (Single Correct Answer)

-1

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

Assertion (A) : Electromagnetic waves carry energy but not momentum.

Reason (R) : Mass of a photon is zero.

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

Both (A) and (R) are true and (R) is the correct explanation of (A)

Both (A) and (R) are true but (R) is not the correct explanation of (A)

(A) is false but (R) is true

(A) is true but (R) is false

JEE Main 2025 (Online) 28th January Evening Shift

MCQ (Single Correct Answer)

-1

The magnetic field of an E.M. wave is given by $\vec{B} = \left( \frac{\sqrt{3}}{2} \hat{i} + \frac{1}{2} \hat{j} \right) 30 \sin \left[ \omega \left( t - \frac{z}{c} \right) \right]$ (S.I. Units).

The corresponding electric field in S.I. units is:

$\overrightarrow{\mathrm{E}}=\left(\frac{1}{2} \hat{i}+\frac{\sqrt{3}}{2} \hat{j}\right) 30 \mathrm{c} \sin \left[\omega\left(\mathrm{t}+\frac{z}{\mathrm{c}}\right)\right]$

$\overrightarrow{\mathrm{E}}=\left(\frac{1}{2} \hat{i}-\frac{\sqrt{3}}{2} \hat{j}\right) 30 \mathrm{c} \sin \left[\omega\left(\mathrm{t}-\frac{z}{\mathrm{c}}\right)\right]$

$\overrightarrow{\mathrm{E}}=\left(\frac{\sqrt{3}}{2} \hat{i}-\frac{1}{2} \hat{j}\right) 30 \mathrm{c} \sin \left[\omega\left(\mathrm{t}+\frac{z}{\mathrm{c}}\right)\right]$

$\overrightarrow{\mathrm{E}}=\left(\frac{3}{4} \hat{i}+\frac{1}{4} \hat{j}\right) 30 \mathrm{c} \cos \left[\omega\left(\mathrm{t}-\frac{z}{\mathrm{c}}\right)\right]$

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