If frequency of electromagnetic wave is 60 MHz and it travels in air along z direction then the corresponding electric and magnetic field vectors will be mutually perpendicular to each other and the wavelength of the wave (in m ) is :

Solution

Physics sir · 3 steps

In air every EM wave moves at c, so the wavelength is just c divided by the frequency.

1. Speed in air. In air an electromagnetic wave travels at almost exactly c = 3 × 10⁸ m s⁻¹. The direction of travel and the perpendicular E⃗ and B⃗ do not change the wavelength.

   λ = c/f

2. Put in numbers. Convert first: 60 MHz = 60 × 10⁶ Hz = 6 × 10⁷ Hz. Then λ = (3 × 10⁸)/(6 × 10⁷) = 5 m.
3. So. The wavelength is 5 m, which is option (b).

The idea to keep. For any EM wave in air or vacuum, use λ = c/f with c = 3 × 10⁸ m s⁻¹. Always turn MHz into Hz by multiplying by 10⁶ before you divide.

Answer from the NTA final answer key. Solution by PrepWiser.