Frequency Formula
Before proceeding to learn about the frequency formula, let us recall what frequency means. Frequency is defined as the number of cycles completed per unit time. It also tells about how many crests go through a fixed point per unit time. Sometimes it is known as reciprocal of time. Frequency is expressed in Hertz(Hz). The frequency formula is used to find the frequency of the wave. Let us understand it better using solved examples.
What Is the Frequency Formula?
Frequency is the total number of occurrences of a repeating event per unit of the given time. There are different frequency formulas to calculate frequency depending upon the quantities known.
Formula 1: The frequency formula in terms of time is given as:
f = 1 / T
where,
 f is the frequency in hertz, and
 T is the time to complete one cycle in seconds
Formula 2: The frequency formula in terms of wavelength and wave speed is given as,
f = 𝜈 / λ
where,
 𝜈 is the wave speed, and
 λ is the wavelength of the wave
Formula 3: Frequency in terms of angular frequency is articulated as
f = ω / 2π
where ω is the angular frequency
Let us understand the frequency formula better through a few solved examples.

Example 1: Using the frequency formula, find the frequency of a wave where one cycle is completed in 0.5s.
Solution:
To find: Frequency
Given:
Time = 0.5s
Using frequency formula
f = 1 / T
f = 1 / 0.5
f = 2
Answer: Frequency is 2Hz.

Example 2: Find the frequency of lightwave when the wavelength of the light is 600nm.
Solution:
To find: Frequency
Given: Wavelength = 600nm
Using frequency formula
f =
𝜈/ λ
f = 3 ×10^{8} / 600 ×10^{9}
f = 5 ×10^{14}
Answer: Frequency is 5 ×10^{14 }Hz.