Question

To and fro motion of a particle about its mean position is called:
A. Frequency
B. Amplitude
C. Vibration
D. Wavelength

Answer 1

Hint: Learn the concepts of frequency, wavelength, vibration and wavelength. Try to define physically what they mean and find their units. The definition of the quantity which is similar to our answer is our answer.

Complete Step-by-Step solution:
We can define frequency as the number of times an event occurs repeatedly per unit time. With the help of frequency, we can find the occurrences of an event. The unit of frequency is hertz (Hz). 1 Hz is equal to one complete event or cycle per unit time.
Amplitude can be defined as the maximum displacement made by the particle from the equilibrium position of the vibration or oscillation. Unit of amplitude is meters.
Consider a wave propagating in medium. We have crests or troughs in a wave. Crests or peak of the wave is the maximum point of the wave and trough is the lowest point. The horizontal distance between two crests or two troughs is called the wavelength of the wave. Simply, we can say that the length of the complete cycle of the wave is called the wavelength.
Vibration can be defined as the motion of a particle with respect to its equilibrium position. When a particle moves in a to and fro motion about its equilibrium position it is called a vibration.
So, the correct option is (C).

Note: We can also define the to and fro motion of a particle about its mean position as oscillation. Oscillation is the motion of a particle in a medium about its mean position. But vibration is defined as the to and fro motion of the body itself due to oscillation.