Target Exam

CUET

Subject

Physics

Chapter

Electromagnetic Waves

Question:

The electric field of a plane electromagnetic wave varies with time of amplitude 2 Vm-1 propagating along z-axis. The average energy density of the magnetic field is (in Jm−3 )

Options:

13.29 × 10−12

8.86 × 10-12

17.72 × 10-12

4.43 × 10-12

Correct Answer:

8.86 × 10-12

Explanation:

$ U=\frac{1}{2}×\frac{1}{2}ε_0E^2 = \frac{1}{2}×\frac{1}{2}×8.85 ×10^{-12} ×(2)^2$

$= 8.85 × 10^{-12} Jm^{-3}$