Target Exam

CUET

Subject

Physics

Chapter

Electromagnetic Waves

Question:

An EM wave travelling in vacuum is described by $\vec{E}=\vec{E}_0 \sin (k x-\omega t) \hat{j}$ and $\vec{B}=\vec{B}_0 \sin (k x-\omega t) \hat{k}$

Which of the following relation is true?

Options:

$E_0 k=B_0 \omega$

$E_0 \omega=B o K$

$E_0 B_0=k \omega$

$\frac{B_o}{E_o}=\sqrt{\omega / k}$

Correct Answer:

$E_0 k=B_0 \omega$

Explanation:

The correct answer is Option (1) → $E_0 k=B_0 \omega$

Relationship between electric field $(E_0)$ and Magnetic field $(B_0)$ is -

$C=\frac{E_0}{B_0}$

and,

Wave number = $\frac{2\pi}{λ}$, Angular frequency = $2\pi v$

$∴\frac{2\pi v×λ}{2\pi}=\frac{E_0}{B_0}$

$⇒B_0×ω=E_0=k$