The dimensions of specific resistance are from Physics Current E

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321.

A galvanometer has a current sensitivity of  1 mA  per division.  A variable shunt is connected across the galvanometer and the combination is put in series with a resistance of 500 Ω  and cell of internal resistance 1 Ω  It gives a deflection of 5 division for shunt of 5 ohm and 20 division for shunt of 25 ohm. The emf of cell is

  • 47.1 V

  • 57.1 V

  • 67.1 V

  • 77.1 V


322.

In the circuit shown, current flowing through 25 V cell is

   

  • 7.2 A

  • 10 A

  • 12 A

  • 4.2 A


323.

Assertion:  It is advantageous to transmit electric power at high voltage.

Reason: High voltage implies high current.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


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324.

The dimensions of specific resistance are

  • [ M L2 T-2 A-1 ]

  • [ M L3 T-3 A-2 ]

  • [ M L3 T-2 A-1 ]

  • [ M L2 T-2 A-2 ]


B.

[ M L3 T-3 A-2 ]

Specific resistance is defined as the resistance offered per unit length and unit cross-sectional area when the known amount of voltage is applied. The mathematical of Specific resistance 

        ρ = R Al

where ρ : specific resistance

          R : Resistance

          A : cross sectional area

           L : Length of the material

dimensions of R = [M L2 T-3 A-2 ]            

           ρ  = M L2 T -3 A-2 L2L

           ρ = [ M L2 T-3 A-2] [L]

          ρ = [ M L T A-2 ]


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325.

Assertion: The dimensional formula for product of resistance and conductance is same as for dielectric  constant.

Reason: Both have dimension of time costant. 

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


326.

A bulb of 25 W. 200 V and another bulb of 100 W, 200 V are connected in series with a supply line of 220 V. Then

  • both bulbs will glow with same brightness

  • both bulbs will get fused

  • 25 W bulb will glow more brightly

  • 100 W bulb will glow more brightly


327.

Assertion:  A bird perches on a high power line and nothing happens to the bird.

Reason:  The level of bird is very high from the ground.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


328.

Assertion: In the following circuit, emf is 2 V and internal resistance of the cell is I Ω and R= 1 Ω, then reading of the voltmeter is 1 V.

  

Reason:  V = E - IR where  E = 2V, I = 2/2 = 1A

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


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329.

Assertion:  A domestic electrical appliance, working on a three pin will continue working even  if the top pin is removed. 

Reason: The third pin is used only as a safety device.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


330.

Assertion:  Ferro magnetic substances become paramagnetic above Curie temperature. 

Reason:  Domains are destroyed at high temperature.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


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