Tag: physics

Questions Related to physics

Explain why, if we strike a table lightly, we hear a soft sound but if we hit the table hard, a loud sound is heard.

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. when a table is striked lightly, vibrations are produced with less amplitude.

  2. when the table is strikes hard, the amplitude is high.

  3. both A and B

  4. none

Show answer
Correct Option: C
Explanation:

If we strike a table lightly the vibrations produced have less amplitude than when we strike the table hard. Since loudness depends on amplitude, soft sound is heard when we strike lightly.

Hertz stands for number of oscillations per:

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. Second

  2. Minute

  3. Hour

  4. Milli second

Show answer
Correct Option: A
Explanation:

Hz is the SI unit of frequency which is defined as wave cycles per unit time..  Since SI unit of time is second. Hz is number of wave cycles per second.

So the answer is A.

A sound wave has a frequency of $10$kHz and wavelength $3$mm. How much time will it take to travel $3$ metre?

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. $0.1$ sec

  2. $1$ sec

  3. $10$ sec

  4. $0.01$ sec

Show answer
Correct Option: A
Explanation:

$V=f\times \lambda$
$=10\times 10^3\times 3\times 10^{-3}=30$
$t=\displaystyle\frac{d}{v}=\frac{3}{30}=0.1$sec.

Frequency of vibration of a particle is 10 Hz. If the amplitude of vibration is doubled, what will be the change in frequency of vibration

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. frequency doubles

  2. frequency becomes halved

  3. frequency remains same

  4. frequency quadruples

Show answer
Correct Option: C
Explanation:

Frequency is a characteristic of source and does not change with amplitude of the wave

The correct option is (c)

The time period of a system executing wave motion depends upon

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. elasticity

  2. inertia

  3. Amplitude

  4. restoring force

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Correct Option: A
Explanation:

Time period of oscillations is directly proportional to square root of modulus of elasticity and inversely proportional to density. Thus option (a) is the correct option

The total energy of sound waves E is related to their frequency n as

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. $E \propto n$

  2. $E \propto \dfrac{1}{n}$

  3. $E \propto \dfrac{1}{n^2}$

  4. $E \propto \dfrac{1}{log n}$

Show answer
Correct Option: A
Explanation:

Energy of a wave is related to its frequency using the formula E = hf, f is the frequency of the wave

A particle performs 20 vibrations in 5 secs. The time period of vibration is

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. 2.5 s

  2. 0.1 s

  3. 0.25 s

  4. 4 s

Show answer
Correct Option: C
Explanation:

Time taken for 1 vibration = 5/20 = 0.25 s

The correct option is (c)

A transverse wave of frequency 50 Hz is reflected from a wall. 50% of the energy of the wave is lost at the wall. The frequency of the reflected wave will be

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. 25 Hz

  2. 50 Hz

  3. 100 Hz

  4. 75 Hz

Show answer
Correct Option: B
Explanation:

Loss in energy only implies loss in amplitude and not in frequency. Since frequency is a characteristic of the source

The correct option is (b)

A particle vibrates 10 times in 1 sec. What is the time period of vibration of the particle

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. 10 Sec

  2. 1 Sec

  3. 0.1 Sec

  4. 0.01 sec

Show answer
Correct Option: C
Explanation:

Time period of vibration is time taken for 1 vibration

Thus 10 vibrations are completed in 1 sec or 1 vibration will taken only 1/10=0.1 sec

The correct option is (c)

Two sound waves having pressure
$P _{1}=2 \times 10^{4} \sin (2\pi \times 10^{4}\ t)Pa$ and 
$P _{2}=4 \times 10^{4} \sin (3\pi \times 10^{4}\ t+\pi /6)Pa$
superimpose with each other. Find the amplitude of resultant wave.

physics sound: production of sound oscillation - amplitude, time period and frequency of oscillation time period, frequency and amplitude of sound oscillatory and periodic motion

  1. $4.47\times 10^{4}\ Pa$

  2. $4.47\ Pa$

  3. $5.67\times 10^{4}\ Pa$

  4. $5.67\ Pa$

Show answer
Correct Option: A