A Level Physics Practice Exam

Which of the following best defines the frequency of a wave?

1. The distance between consecutive crests

2. The number of complete waves passing a point in one second

3. The amplitude of the wave

4. The speed of the wave in a medium

The correct answer is: The number of complete waves passing a point in one second

The frequency of a wave is defined as the number of complete waves that pass a given point in one second. This measurement is typically expressed in hertz (Hz), where one hertz corresponds to one wave passing a point per second. Frequency directly relates to how quickly the wave oscillates; higher frequency means more cycles occur in a given time frame, which influences the energy and behavior of the wave. The other definitions provided in the choices pertain to different aspects of wave characteristics. The distance between consecutive crests refers to the wavelength, which measures the length of one complete cycle of the wave. The amplitude represents the maximum displacement of a point on the wave from its equilibrium position, indicating the wave's intensity or strength, but does not relate to frequency. The speed of the wave in a medium refers to how fast the wave travels through that medium and is a product of both its frequency and wavelength, described by the equation: speed = frequency × wavelength. Thus, the definition that describes the frequency specifically is the one that correctly identifies the number of waves passing a point in one second.