Question

The number of vibrations made by a vibrating body in one second is called its:
(A) Wavelength
(B) Time period
(C) Amplitude
(D) Frequency

Answer 1

From its standard stationary position, a vibrating object moves back and forth. When the object moves from one extreme position to the other extreme, and back again, a complete cycle of vibration happens.

Complete Step-by-Step Solution:
A wavelength is defined as the distance from equilibrium between the maximum displacement of the amplitude. It is the space produced in a periodic wave, the distance over which the form of the wave is repeated. It is usually measured by taking the distance between corresponding points of the same phase or different spatial wave patterns.
In sinusoidal wave motion, the particles move with the passage of time around the mean position. The particles rise until they reach the crest's highest point, and then continue to fall until they reach the trough's lowest point. In a uniform pattern, the cycle repeats itself. The time period of a wave's oscillation is defined as the time taken to complete one such oscillation by any element of the string.
A sound wave's amplitude is the measure of the wave's height. A sound wave's amplitude can be defined as the loudness or the amount of maximum displacement of the medium's vibrating particles from their mean position when the sound is generated. It is the distance between the crest or trough and the wave's average position.
Frequency is the number of complete wave cycles passing through the point at the time of the unit. The number of cycles that are completed in one second by a vibrating object is called frequency. The frequency unit is hertz ( $Hz$ ). One hertz is equivalent to one cycle a second.

Hence, the correct option is (D.)

Note: Frequency describes the number of waves passing through a fixed place in a given amount of time. So, if the time it takes for a wave to pass is $0.5$ second, the frequency is $2$ per second.