Home
Class 11
PHYSICS
(a) The power of sound from the speaker ...

(a) The power of sound from the speaker of a radio is 20 mW. By turning the knob of volume control the power of sound is increased to 400 mW, What is the power increase in dB as compared to original power? (b) How much more intense is an 80 dB sound than a 20 dB whisper?

A

13 dB

B

10 dB

C

20 dB

D

800 dB

Text Solution

Verified by Experts

The correct Answer is:
A
`dB=10"log"(I_(2))/(I_(1))=10 "log"(400)/(20)=10 log20`
`10(1+0.3)=13dB`
Promotional Banner

Topper's Solved these Questions

  • WAVES AND OSCILLATIONS

    ALLEN|Exercise Part-1(Exercise-02)|19 Videos

  • WAVES AND OSCILLATIONS

    ALLEN|Exercise Part-1(Exercise-03)|31 Videos

  • WAVES AND OSCILLATIONS

    ALLEN|Exercise Part-3(Example)|32 Videos

  • SEMICONDUCTORS

    ALLEN|Exercise Part-3(Exercise-4)|51 Videos

Similar Questions

Explore conceptually related problems

How Many times more intense is a 60 dB sound than a 30 dB sound ?

The power of sound from the speaker of radio is 10 W. Now, the power of sound from the speaker of the radio is increased to 400 W by increasing the volume of the radio. The power increased in dB as compared to original power is nearly

How much intense is 80 dB sound in comparision to 40 dB?

If the sound level in a room is increased from 50 dB to 60 dB, by what factor is the pressure amplitude increased ?

A sound produced by one musical instruments is 20dB more intense as compared to the sound by another instrument. What are their relative powers?

The speaker of a public address system emits 20 kW power, considering it a point source. What is the sound intensity level at a point 4.00 m away?

A sound increases its decibel reading from 20 "to" 40 dB . This means that the intensity of the sound

Loudness of sound from an isotropic point source at a distace of 70cm is 20dB . What is the distance (in m) at which it is not heard.

In an electron microscope the acclerating voltage is increased from 20kv to 80kv. The resolving power of the microscope will become

A line source of sound of length 10 m, emitting a pulse of sound that travels radially outward from the source. The power of the source is P = 1.0.x 10^4 W What is the approximated intensity '/' of the sound when it reaches a distance of 10 m from the source?

ALLEN-WAVES AND OSCILLATIONS-Part-1(Exercise-01)
  1. A cylindrical tube, open at both ends, has a fundamental frequency f i...

    Text Solution

    |

  2. An organ pipe P(1) closed at one end vibrating in its first harmonic a...

    Text Solution

    |

  3. An open pie is suddenly closed at one end with the result that the fre...

    Text Solution

    |

  4. The maximum length of a closed pipe that would produce a just audible ...

    Text Solution

    |

  5. A cylindrical tube (L = 129 cm) is in resonance with in tuning fork of...

    Text Solution

    |

  6. A closed organ pipe of radius r(1) and an open organ pipe of radius r(...

    Text Solution

    |

  7. Plane sound waves of wavelength 0.12 m are incident on two narrow slit...

    Text Solution

    |

  8. Two vibrating tunign forks produce progessive waves given by y(1)=4 ...

    Text Solution

    |

  9. Frequency of tuning fork A is 256 Hz. It produces 4 beats/second with ...

    Text Solution

    |

  10. Length of a sonometer wire is either 95 cm or 100 cm. In both the case...

    Text Solution

    |

  11. Two open pipes of length 25 cm and 25.5 cm produced 0.1 beat/second. T...

    Text Solution

    |

  12. 16 tuning forks are arranged in increasing order of frequency. Any two...

    Text Solution

    |

  13. Two tuning forks having frequency 256 Hz (A) and 262 Hz (B) tuning for...

    Text Solution

    |

  14. Two open pipes of length L are vibrated simultaneously. If length of o...

    Text Solution

    |

  15. (a) The power of sound from the speaker of a radio is 20 mW. By turnin...

    Text Solution

    |

  16. A sound absorber attenuates the sound level by 20 dB. The intensity de...

    Text Solution

    |

  17. A whistle giving out 450 H(Z) approaches a stationary observer at a sp...

    Text Solution

    |

  18. A person feels 2.5% difference of frequency of a motor-car horn. If th...

    Text Solution

    |

  19. Two trains A and B are moving in the same direction with velocities 30...

    Text Solution

    |

  20. A whistle revolves is a circle with angular velocity w= 20 rad/s using...

    Text Solution

    |