# Oscillations and Waves (NEET Physics): Questions 159 - 164 of 192

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## Question number: 159

» Oscillations and Waves » Doppler Effect in Sound

### Question

A police car moving at 22 m/s, chases a motorcyclist. The police man sounds his horn at 180 Hz, while both of them move towards a stationary siren of frequency 162 Hz. Calculate the speed of the motorcycle, if it is given that he does not observes any beats

### Choices

Choice (4) | Response | |
---|---|---|

a. | 33 m/s | |

b. | 22 m/s | |

c. | Zero | |

d. | 28.7 m/s |

## Question number: 160

» Oscillations and Waves » Harmonics

### Question

The loudness and the pitch of a sound depends on

### Choices

Choice (4) | Response | |
---|---|---|

a. | Intensity and frequency | |

b. | Frequency and velocity | |

c. | Intensity and velocity | |

d. | Frequency and number of harmonics |

## Question number: 161

» Oscillations and Waves » Harmonics

### Question

A string on a musical instrument is 70 cm long and its fundamental frequency is 235 Hz. If the desired frequency of 950 Hz, is to be produced, the required length of the string is

### Choices

Choice (4) | Response | |
---|---|---|

a. | 22.7 cm | |

b. | 12.3 cm | |

c. | 17.3 cm | |

d. | 16.5 cm |

## Passage

A plate was cut from a quartz crystal and is used to control the frequency of an oscillating electrical circuit. Longitudinal standing waves are set up in the plate with displacement antinodes at opposite faces.

The fundamental frequency of vibration is given by the equation . Here s is thickness of the plate and density of quartz is 2658.76 kg/m ^{3}.

## Question number: 162 (1 of 2 Based on Passage) Show Passage

» Oscillations and Waves » Harmonics

### Question

Young’s modulus of elasticity for quartz is -

### Choices

Choice (4) | Response | |
---|---|---|

a. | 8.76 ⨯ 10 | |

b. | 7 ⨯ 10 | |

c. | 2 ⨯ 10 | |

d. | Information insufficient |

## Question number: 163 (2 of 2 Based on Passage) Show Passage

» Oscillations and Waves » Harmonics

### Question

If the quartz plate is vibrating in 3 ^{rd} harmonic while measuring the frequency of 1.2 ⨯ 10 ^{6} Hz, then the thickness of the plate is,

### Choices

Choice (4) | Response | |
---|---|---|

a. | 7.175 cm | |

b. | 0.07 cm | |

c. | 6.02 cm | |

d. | 71.75cm |

## Question number: 164

» Oscillations and Waves » Beats

### Question

Two whistles *A* and *B * produce notes of frequencies 660 Hz and 596 Hz respectively. There is a listener at the midpoint of the line joining them. Now the whistle *B * and the listener start moving with speed 30 m/s away from the whistle A. If speed of sound be 330 m/s, how many beats will be heard by the listener?

### Choices

Choice (4) | Response | |
---|---|---|

a. | 4 | |

b. | 2 | |

c. | 8 | |

d. | 6 |