Target Exam

CUET

Subject

Physics

Chapter

Electromagnetic Waves

Question:

A plane electromagnetic wave of frequency 25 GHz is propagating in vacuum along the z-direction. At a particular point in space and time, the magnetic field is given by a value $5×10^{-8} T$ along Y-direction. The corresponding electric field is

(speed of light $c= 3 × 10^8\, m/s$)

Options:

15 V/m, along +X axis

15 V/m, along -X axis

1.66 V/m, along +X axis

1.66 V/m, along -X axis.

Correct Answer:

15 V/m, along +X axis

Explanation:

Given:

Frequency $f = 25 \times 10^{9} \ \text{Hz}$

Magnetic field $B = 5 \times 10^{-8} \ \text{T}$

In vacuum, the relation between electric field and magnetic field is

$E = cB$

where $c = 3 \times 10^{8} \ \text{m/s}$.

$E = (3 \times 10^{8})(5 \times 10^{-8})$

$E = 15 \ \text{V/m}$

Answer: 15 V/m, along +X axis