We can use 2 equations to solve this.
First one, C= fλ
Where C is speed of light (3 x 10⁸ m s⁻¹), f is the frequency (Hz) and λ is the wavelength of the wave (m).
Second one, E = hf
Where E is the energy (J), f is the frequency (Hz) and h is the planck's constant (6.626 × 10⁻³⁴ J s).
From first equation,
C = fλ
f = C/λ
= 3 x 10⁸ m s⁻¹ / 4.5 x 10⁻⁷ m
From second equation,
E = hf
= 6.626 × 10⁻³⁴ J s x (3 x 10⁸ m s⁻¹ / 4.5 x 10⁻⁷ m)
= 4.417 x 10⁻¹⁹ J
Hence, the energy of the photon is 4.417 x 10⁻¹⁹ J.
