Answer:
Explanation:
[tex]c = f \lambda[/tex]
where c = speed of light (3x10^8m/s)
f = frequency
[tex]\lambda[/tex] = wavelength.
We can solve that the frequency is (3x10^8)/(420 x 10^-9) = 7.14x10^14 Hz
Also, E = hf where h = 6.62x10^-34.
So the energy is (6.62x10^-34) x (7.14x10^14) = 4.73x10^-19 J.
Hope this helps and tell me if I made any mistakes.
