If vibration of string is to be two times, then tension in t

Subject

Physics

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

The spring extends by x on loading, then energy stored by the spring is (if T is the tension in spring and k is
spring constant

  • T22k

  • T22k2

  • 2kT2

  • 2T2k


12.

A cylinder contains 10kg of gas at pressure of 107 N/m2. The quantity of gas taken out of the cylinder, if final pressure is 2.5×106 N/m2 will be( temperature of gas is constant)

  • 15.2 kg

  • 3.7 kg

  • zero

  • 7.5 kg


13.

A resonance air column of length 40 cm resonates with tunning fork of frequency 450Hz. Ignoring end corrections , the velocity of sound in air will be

  • 1020m/s

  • 920m/s

  • 820m/s

  • 720m/s


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14.

If vibration of string is to be two times, then tension in the string must be made

  • Eight times

  • Four times

  • Twice

  • Half


B.

Four times

Here initial vibration n1=n , final vibration n2 =2n

Initial tension T1 =T

Vibration frequency of string

n=12lTmnTHence, n1n2=T1T2or           T1T2=n1n22=n2n2=12or   T2=4T1


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15.

A siren emitting sound of frequency 500 Hz is going away from a stationary listener with a speed of 50 m/s, the frequency of sound heard directly from the siren is 

  • 286.5 HZ

  • 481 Hz

  • 434.2 Hz

  • 580 Hz


16.

The kinetic energy of one molecule of a gas at normal temperature and pressure will be (k = 8.31 J/mole K)

  • 1.7×103 J

  • 10.2×103 J

  • 3.4×103 J

  • 6.8×103 J


17.

A charged particle is suspended equillibrium in a uniform vertical electric field of intensity 2000V/m. If mass of the particle is 9.6×10-16 kg, the charge on it and excess number of electrons on the particle respectively are (g=10m/s2)

  • 4.8×10-19 C,3

  • 5.8×10-19 C,4

  • 3.8×10-19C, 2

  • 2.8×10-19 C, 1


18.

A transmitting station transmits radiowaves of wavelength 360 m. Calculate the inductance of coil required with a condenser of capacity 1.20 μF in the resonant circuit to receive them

  • 3.07×10-8 H

  • 2.07×10-8 H

  • 4.07×10-8 H

  • 6.07×10-8 H


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19.

A circular coil of mean radius of 7 cm and having 4000 turns is rotated at the rate of 1800 revolutions per minute in the earth's magnetic field (B=0.5 gauss), the emf induced in coil will be

  • 1.158 V

  • 0.58 V

  • 0.29 V

  • 5.8 V


20.

The peak value of alternating current is 52 ampere. The mean square value of current will be

  • 5 A

  • 2.5 A

  • 52 A

  • None of the above


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