To measure wave frequency, you can follow these methods:
- Counting Waves Passing a Point: Count the number of complete wave cycles (crests or troughs) passing a fixed point in a set time interval, typically one second. The frequency is the number of cycles per second, measured in hertz (Hz). For example, if 10 waves pass in 10 seconds, the frequency is 1 Hz (10 ÷ 10)
- Using Period Measurement: Measure the period TTT, which is the time taken for one complete wave cycle. Frequency fff is the inverse of the period: f=1Tf=\frac{1}{T}f=T1. For instance, if one cycle takes 0.5 seconds, the frequency is 2 Hz (1 ÷ 0.5)
- Using Wave Speed and Wavelength: If you know the wave speed vvv and wavelength λ\lambda λ, frequency can be calculated by the formula f=vλf=\frac{v}{\lambda}f=λv. For example, a wave traveling at 6 m/s with a wavelength of 2 m has a frequency of 3 Hz (6 ÷ 2)
Practical example with a ripple tank:
- Set up the ripple tank with water and generate waves.
- Count how many waves pass a point in 10 seconds and divide by 10 to get frequency.
- Alternatively, measure wavelength and use the wave speed to find frequency
In summary, wave frequency is measured by counting wave cycles per unit time, measuring the period and taking its inverse, or calculating from wave speed and wavelength using the formula f=vλf=\frac{v}{\lambda}f=λv.
