Question

The number of cycles an oscillator completes in each second is called its
(A) Frequency
(B) Velocity
(C) Amplitude
(D) Angular velocity

Answer 1

Hint: An oscillator is an object which undergoes an oscillatory motion which is a type of motion that repeats itself after a period of time in a to and fro manner. The number of cycles an oscillator completes in a second is a measure how quickly the next cycle begins.

Complete answer:
An oscillatory motion is a type of periodic motion which repeats itself every time in such a way that it reverses its own direction after a particular period of time. An oscillator is an object which undergoes this type of motion. An example of oscillatory motion is the motion of a pendulum bob. A pendulum bob swings to and fro, i.e. reverses its own direction at some point and then repeats the process continually.
Now, a cycle is defined as the one complete to and fro movement of an oscillator. When an oscillator moves to, that is only a half cycle. But when it completes it’s fro movement, then it’s now a complete cycle. The number of cycles an oscillator completes in each second is a measure of how fast the cycle completes, hence the measure of how fast the next cycle begins, hence again, the measure of how frequent the cycle takes place. Thus it is called the frequency.
Hence the number of cycles an oscillator completes in each second is called its frequency,
Therefore, the correct option is (A), frequency.

Note:
Alternatively, if one can identify the unit of each term in the options, then we can compare to the unit generated by the definition in the question.
Number of cycles in each second means that the quantity must have a unit of cycles per second in the SI system; it is written as $ {s^{ - 1}} $ cycle as no SI symbol. Also, the unit of frequency is $ {s^{ - 1}} $ .