Question

Calculate the frequency of a photon of wavelength 4000 angstrom.

Answer 1

Wavelength
=4000 A°
=4000× 10^-10 m
=4× 10^-7 m

We know that,
C= frequency × wavelength

=>frequency = C/wavelength
=(3× 10^8)/(4× 10 ^-7)
= 7.5× 10^14 Hz

Hope this helps!

Answer 2

Given:

• Wavelength, λ = 4000 * $10^{-10}$ m = 4*$10^{-7}$ m

To Find:

• Frequency of Photon.

Solution:

• We have a formula saying c = λf
• Where c is the speed of light in Vaccum, f is the frequency and λ is the wavelength.
• We already know that, c = 3*$10^8$ m/s
• Rearranging the formula to find frequency, f = c/λ
• Substituting the values in the equation we get,
• f = $\frac{3*10^8}{4*10^{-7}} = 0.75 * 10^{15}$  
• f = 7.5*$10^{14}$  Hz

∴ The frequency f = $7.5*10^{14}$ Hz.