Decibels

Q.

What is the SI unit of loudness?

Q.

Unit of intensity of sound is _______.

1. volt
2. metre
3. kelvin
4. decibel

Q.

Decibel (dB) is a unit of loudness of sound. It is defined in a manner such that when the amplitude of the sound is multiplied by a factor of $\sqrt{10}$, the decibel level increases by 10 units. Loud music of 70 dB is being played at a function. To reduce the loudness to a level of 30 dB, the amplitude of the instrument playing music has to be reduced by a factor of:

1. 10

2. 100

3. $10\sqrt{10}$

4. $100\sqrt{100}$

Q. Question 6
Loudness of sound is measured in units of

(a) Decibel (dB)
(b) Hertz (Hz)
(c) Metre (m)
(d) Metre/second (m/s)

Q.

A firecracker has a sound intensity od 145 dB, which is exactly an average of sound intensities of jet engine at take off and fighter jet launch. Calculate the required scales for jet engine at take off and fighter jet.

1. 140, 130

2. 140, 150

3. 150, 155

4. 140, 155

Q.

A person is hearing two sounds. The loudness of both the sounds is different. The intensity of both sounds can be the same.

1. True
2. False

Q.

The logarithmic scale is used to describe decibel because a very large range of ratios can be represented by a convenient number.

1. False

2. True

Q. Loudness of a sound is measured in_________.

1. hertz
2. decibel
3. metre
4. metre per second

Q. Two sound waves have amplitudes in the ratio 2:5. Ratio of the intensities of the sound waves is:

1. 2:5
2. 5:2
3. 4:25
4. 25:4

Q. Assertion :A $80dB$ sound has twice the intensity of a $40dB$ sound. Reason: Loudness of a sound of a certain intensity I is defined as
$L_{dB}=10{\log }_{10}{\frac{I}{I}}_o$

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason are correct

Q. What is the S.I. unit of intensity of sound?

1. Decibel
2. Metre
3. Joule
4. Newton

Q.

Loudness is measured in which unit?

1. Hz

2. dB

3. m/s

4. All of the above

Q. the intensity of sound of50 dB is

Q. The unit of loudness is :

1. cm
2. second
3. hertz
4. decibel

Q. Decibel is a unit of

1. Intensity of light
2. X-rays radiation capacity
3. Sound loudness
4. none of these