Question

The time period of a simple pendulum is 0.2sec. What is its frequency of oscillation?
(A) 0.5Hz
(B) 5Hz
(C ) 50Hz
(D) 1Hz

Answer 1

Hint: The frequency is the reciprocal of its time period. The unit of frequency is Hertz and the time period is calculated in seconds. Thus one frequency of oscillation is defined as the number of cycles that a wave travels in a second. Since the frequency is the reciprocal of its time period, by taking the reciprocal of the given value of the time period we will get the frequency.
Formula used:
$f=\dfrac{1}{T}$
where f is the frequency.
T is the time period.

Complete step-by-step solution
Given that,
Time period, T=0.2sec
Since the frequency is the reciprocal of its time period, by taking the reciprocal of the given value of the time period we will get the frequency.
Thus, $f=\dfrac{1}{T}$
$\Rightarrow f=\dfrac{1}{0.2}$
$\therefore f=5Hz$
Thus one frequency of oscillation is defined as the number of cycles that a wave travels in a second. The unit of frequency is Hertz and the time period is calculated in seconds. Since the frequency is the reciprocal of the time period, the unit of frequency becomes the reciprocal of the second. That is, per second which is also known as Hertz.
Hence, option (B) is correct.

Note: The unit of frequency is Hertz and the time period is calculated in seconds. Thus one frequency of oscillation is defined as the number of cycles that a wave travels in a second. Otherwise, the frequency can be defined as the ratio of the velocity of the wave to its wavelength. Where, is the unit of velocity is meter per second, and the unit of wavelength is meter. Hence, the unit of frequency becomes the reciprocal of the second. That is, per second which is also known as Hertz.