Wavelength to Frequency Formula

The velocity of light, v, is the product of its wavelength, λ , and its frequency, f. This means that the wavelength is the velocity, v, divided by the frequency, f.

Wavelength of light = velocity of light / frequency of light

λ = v/f

λ = Wavelength of light, meters

v = Velocity of light (c = 3.0 x 10⁸ m, for speed of light if not otherwise defined)

f = frequency of light, Hz

Wavelength to Frequency Formula Questions:

1) One of the violet lines of a Krypton laser is at 406.7 nm. What is its frequency?

Answer: The velocity, v, of light is 3 x 10⁸m/s.

The wavelength, λ = 406.7 nm = 406.7 x 10^-9 m.

λ = v/f

f = v/λ

f = 3 x 10⁸ / 406.7 x 10^-9

f = 1.22 x 10 ²⁰ Hz

2) If a wave is moving through a medium at 700 m/s, and 2500 waves pass point A in one minute, what is the wavelength?

Answer:

The velocity of the wave, v = 700 m/s. The frequency of the wave, f = 2500/min x 1 min/60 sec = 41.67 waves/sec.

λ = v/f

λ = (700 m/s) / (41.67 waves/sec)

λ = 16.8 m

3) A beam of light has a wavelength of 350 m. What is the frequency of the light?

Answer: The speed of light, v = 3 x 10⁸m/s and the wavelength, λ = 350 m.

λ = v/f

f = v/λ

f = (3 x 10⁸ m/sec)/ (350 m)

f = 857142.86 waves/sec = Hz