Which of the following statement is correct about electromagnetic waves?

Electromagnetic Waves

NEET

Both electric field vectors and magnetic field vectors are opposite in phase

Electromagnetic waves always require a medium for propagation

The energy in electromagnetic wave is divided equally between electric and magnetic fields

Both (2) and (3)

Solution:

Let's analyze each statement:

(1) Both electric field vectors and magnetic field vectors are opposite in phase: This statement is incorrect. In an electromagnetic wave, the electric field vector (E) and the magnetic field vector (B) oscillate in phase with each other. They are perpendicular to each other and also perpendicular to the direction of propagation of the wave.

(2) Electromagnetic waves always require a medium for propagation: This statement is incorrect. Electromagnetic waves are unique in that they do not require a material medium for their propagation. They can travel through a vacuum, which is why light from the Sun can reach Earth through the vacuum of space.

(3) The energy in electromagnetic wave is divided equally between electric and magnetic fields: This statement is correct. In an electromagnetic wave, the average energy density associated with the electric field ( $u_E$ ) is equal to the average energy density associated with the magnetic field ( $u_B$ ). That is, $u_E = u_B = \frac{1}{2} \epsilon_0 E^2 = \frac{1}{2\mu_0} B^2$ . This implies that the total energy of the electromagnetic wave is equally distributed between its electric and magnetic field components.

(4) Both (2) and (3): This statement is incorrect because statement (2) is false.

Therefore, the correct statement is (3).

Which of the following statement is correct about electromagnetic waves?

Solution:

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