As we know,
Speed of light (c) = Frequency (f) x Wavelength (λ)
Given,
C = 3 x 108 m s-1
Frequency range = 3.75 × 1014 Hz to 7.5 × 1014 Hz.
Let, f1 = 3.75 × 1014 Hz
Substituting the values in the formula,
3×108=3.75×1014×λλ=3.75×10143×108⇒λ=0.8×10−6m⇒λ=8000×10−10m
As, 1 Å = 10-10 m
Therefore,
λ1 = 8000 Å
Let, f2 = 7.5 × 1014 Hz
Substituting the values in the formula,
3×108=7.5×1014×λλ=7.5×10143×108⇒λ=0.4×10−6m⇒λ=4000×10−10m
As, 1 Å = 10-10 m
Therefore,
λ2 = 4000 Å
Therefore, the wavelength range is 4000 Å to 8000 Å.