The magnetic moment has dimensions of from Physics NEET Year 200

Subject

Physics

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

21.

Assertion:  The Carnot cycle is useful in understanding the performance of heat engines. 

Reason:  The Carnot cycle provides a way of determining the maximum possible efficiency achievable with reservoirs of given temperatures.

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

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

  • If assertion is true, but reason is false

  • Both assertion and reason are false statements


22.

Assertion: Perspiration from human body helps in cooling the body.

Reason: A thin layer of water on the skin enhances its emissivity.

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

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

  • If assertion is true, but reason is false

  • Both assertion and reason are false statements


23.

Assertion:  When a glass of hot milk is placed in a room and allowed to cool, its entropy decreases. 

Reason:  Allowing hot object to cool does not violate the second law of thermodynamics.

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

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

  • If assertion is true, but reason is false

  • Both assertion and reason are false statement


24.

Assertion: A thin stainless steel needle can lay floating on a still water surface. 

Reason:  Any object floats when the buoyancy force balances the weight of the object.

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

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

  • If assertion is true, but reason is false

  • Both assertion and reason are false statements


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25.

Two parallel large thin metal sheets have equal surface charge densities ( σ = 26.4 × 10-12 C/m2 ) of opposite signs. The electric field between these sheets is

  • 1.5 N/C

  • 1.5 × 10-10 N/C

  • 3 N/C

  • 3 × 10-10 N/C 


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26.

The magnetic moment has dimensions of

  • [ LA ]

  • [ L2A ]

  • [ L T-1 A ]

  • [ L2 T-1 A ]


B.

[ L2A ]

The magnetic moment of a magnet is a quantity that determines the torque. It will experience in an exernal magnetic field. A loop of electric current, a bar magnet, an electron, a molecule and a planet all have magnetic moments.

Magnetic moment of a circular coil ( solenoid also ) is

     μ  =  NIA

where μ  = magnetic moment.

          N = Number of turns of coil ( for a simple circular coil)

          I = Current in the coil

         A = Area ( magnetic moment is along area vector )

The S.I unit of magnetic moment is Am2.

Therefore its dimensions is [ L2 A ].


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27.

Five capacitors, each of capacitance value C are connected as shown in the figure. The ratio of
capacitance between P and R, and the capacitance between P and Q is

    

  • 3 : 1

  • 5 : 2

  • 2 : 3

  • 1 : 1


28.

The spatial distribution of the electric field due to two charges (A, B) is shown in figure. Which one of the following statements is correct?

  • A is +ve and +B is -ve and A > B

  • A is -ve and B is +ve; A = B

  • both are +ve but A > B

  • both are -ve but A > B


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29.

Circular  loop  of  a  wire  and a  long  straight  wire  carry currents  Ic  and  Ie respectively  as shown in figure. Assuming  that  these  are  places  in  the same plane, the magnetic  field  will be  zero  at  the  centre of  the loop when separation  H is

  • Ie RIc π

  • Ic RIe π

  • π IcIe R

  • Ie πIc R


30.

A metallic ring is dropped down, keeping its plane perpendicular to a constant and horizontal magnetic field. The ring enters the region of magnetic field at I = 0 and completely emerges out at  t = T sec. The current in the ring varies as


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