Question

The property which is not of an electromagnetic wave travelling in free space is that :

• A. they are transverse in nature.
• B. the energy density in electric field is equal to energy density in magnetic field.
• C. they travel with a speed equal to $\frac{1}{\sqrt{\mu_0\epsilon_0}}$.
• D. they originate from charges moving with uniform speed.

Answer 1

The Correct Option is D

Step 1: Analyze the Properties of Electromagnetic Waves

Electromagnetic waves consist of oscillating electric and magnetic fields that are perpendicular to each other and to the direction of propagation, making them transverse in nature.

Their energy density in the electric and magnetic fields is equal.

They travel in free space with a speed:

$$c = \frac{1}{\sqrt{\mu_0 \epsilon_0}}$$

Where:

$c$ = Speed of electromagnetic waves in free space

$\mu_0$ = Permeability of free space

$\epsilon_0$ = Permittivity of free space

Step 2: Address the Incorrect Property

Electromagnetic waves are produced by accelerated charges, not charges moving with uniform speed. Thus, option (3) is incorrect.

Step 3: Conclusion

The property not belonging to electromagnetic waves is that they originate from charges moving with uniform speed.