Noise level inside a jet air liner in normal flight is about __________ decibels.

Noise level heard inside a bus in busy city traffic or inside a sub-way train corresponds to about __________ decibels.

A

75

B

95

C

120

D

140

Power gain in decibels is equal to voltage gain in decibels only when

A

Input impedance is equal to output impedance

B

Output impedance is zero

C

Never

D

Input impedance is zero

The maximum permissible noise level to which a man working in a chemical plant can be exposed for eight hours per day is about __________ decibels.

A

60

B

90

C

105

D

120

Noise level in a quiet private business office is about __________ decibels.

A

25

B

50

C

70

D

85

Maximum permissible limit of industrial noise as recommended by World Health Organisation (WHO) is __________ decibels.

A

35

B

75

C

95

D

105

A jet of water is striking at the centre of a curved vane moving with a uniform velocity in the direction of jet. For the maximum efficiency, the vane velocity is ________ of the jet velocity

A

One-half

B

One-third

C

Two-third

D

Three-fourth

The force exerted by a jet of water impinging normally on a plate which due to the impact of jet, moves in the direction of jet with a velocity v is

A

$$\frac{{{\text{wa}}\left( {{\text{V}} - {\text{v}}} \right)}}{{2{\text{g}}}}$$

B

$$\frac{{{\text{wa}}\left( {{\text{V}} - {\text{v}}} \right)}}{{\text{g}}}$$

C

$$\frac{{{\text{wa}}{{\left( {{\text{V}} - {\text{v}}} \right)}^2}}}{{2{\text{g}}}}$$

D

$$\frac{{{\text{wa}}{{\left( {{\text{V}} - {\text{v}}} \right)}^2}}}{{\text{g}}}$$

Shouting by a man at his full voice corresponds to a voice level of about __________ decibels.

A

25

B

50

C

80

D

120

In air breathing jet engine, the jet is formed by expanding

A

Highly heated atmospheric air

B

Solids

C

Liquid

D

Plasma

A negative gain margin expressed in decibels means a/an __________ system.

A

Stable

B

Unstable

C

Critically damped

D

None of these

Noise level inside a jet air liner in normal flight is about __________ decibels.

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