As we know, a charged particle oscillates about its mean equilibrium position with a frequency of 109 Hz.
Therefore, the frequency of an electromagnetic wave produced by the oscillator is the same as that of a charged particle oscillating about its mean position i.e., 109 Hz.
The wavelength of light is given by,
λ=cv ...(i)
Where,
v=109 Hz, frequency of electromagnetic wave
c=3×108 m/s
By putting the values in equation (i) we get,
λ=3×108109=0.3 m
As the frequency of electromagnetic wave is 109 Hz, thus it will fall in the region of radio waves.
Final Answer: Option (a), (c) ,(d)