23 Electromagnetic waves in vacuum have a frequency of 120x1

23. Electromagnetic waves in vacuum have a frequency of 1.20x101 Hz. The wave length is (A) 3.00x10 m (B) 2.50x10 m (C) 4.00x10 m (D) Undetermined

Solution

Answer (B)

Solution :

For electro magnetic waves ,Velocity = 3 x 10^8 m/s ( speed of light)

Also Velocity = Frequency x wavelength

So Wavelength = Velocity/ Frequency = 3 x 10^ 8 / 1.2 x 10^ 19 Hz = 2.5 x 10 ^-11 m