Question

Fill in the blanks with suitable words.
(a) Time taken by an object to complete one oscillation is called ________.
(b) Loudness is determined by the ________ of vibration.
(c) The unit of frequency is _______.
(d) Unwanted sound is called _______.
(e) Shrillness of a sound is determined by the ________ of the vibration.

A. Time period, Hertz, Noise, Frequency, Amplitude
B. Time period, Amplitude, Hertz, Noise, Frequency
C. Time period, Amplitude, Hertz, Frequency, Noise
D. Amplitude, Hertz, Noise, Frequency, Time period

Answer 1

Hint: A sound wave is a longitudinal wave, which means that the oscillation of the particles constituting the wave is in the same direction as that of wave propagation. This wave has characteristic frequency and amplitude.

Complete answer:
The propagation of sound is caused by the particles of the medium in which the sound is propagating. The particles tend to execute a to and fro motion. Therefore, the wave becomes a region of compressions and rarefactions. The time period of oscillation of the particles becomes the time period of the wave. Time period of oscillation for a particle is the time it takes to complete one oscillation.
Next, we know that the inverse of the time period is the frequency of oscillation. We can say that frequency is the amount by which the particle oscillates in unit time (1s). The unit of frequency is therefore, $s^{-1}$ which is also Hertz.
We can say this by experience that louder sounds propagate more energy, thus, loud sounds tend to increase the amount of distance about the mean position of the particle. Therefore, loudness is determined by the amplitude of the oscillation.
Shrillness is described as the harshness or pitch of the sound. This is caused at higher frequencies.
Lastly, noise is unwanted sound.

So, the correct answer is “Option B”.

Note:
If one even does not remember many details about sound propagation, one can still know that noise is unwanted sound. From a given set of options, it is only option (B) that has noise on the second last position (or the correct position) according to the blanks. Therefore, one can blindly tick option (B) as the right answer without even bothering about the rest of the blanks, although it is always good to know the facts.