Magnetic energy per unit volume is represented by from Phys

Subject

Physics

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

21.

In series LCR circuit, the phase difference between applied voltage and current is

  • Positive when XL > XC

  • positive when XC > XL

  • 90o

  • 0o


22.

What is the dimensions of a magnetic field B in terms of C ( = coulomb ), M, L, T?

  • [ M1 L-1 T-2 C ]

  • [ M1 L0 T-1 C-1 ]

  • [ M1 L0 T-2 C ]

  • [ M1 L0 T-1 C ]


23.

What is the mechanical equivalent of spring constant kin LC oscillating circuit?

  • 1L

  • 1C

  • LC

  • 1L C


24.

Energy stored in between the plates of parallel plate capacitor of area A, separated by distance d is

  • 12ε0 E2 Ad 

  • 12ε0 E2 Ad

  • 12ε0dE2 A

  • 12 A dε0 E2


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25.

Magnetic energy per unit volume is represented by

  • B22 μ0

  • B22 μ0 2

  • 2 B2μ0

  • B2μ0


A.

B22 μ0

The emf induced in an inductor 

         Iε = I2 R + LI dIdt

This expression indicates that the rate at which energy is supplied by the battery (Iε ) equals the sum of the rate at which energy energy delivered to the resistor I2R and the rate at which energy is stored in the inductor L dIdt 

Now U is the energy stored in inductor at any time, rate of change of energy is given by

         dUdt = L I dIdt

To find the total energy stored in the inductor, dU = LI

         U =  dU 

             = 0I LI dI

         U = 12L I2             ....(i)

where L is constant.

This expression represents the energy stored in the magnetic field of the inductor when current is I.

The energy stored in the electric field of capacitor 

       U = Q22C

Now energy density of magnetic field 

       L = μ0n2 Al

The magenetic field of a  solenoid is given by

        B = μ0 nI

Substituting the expression for L and  I = Bμ0 n 

Put above value in eq. (i)

       U = 12μ0n2 Al Bμ0 n2

⇒    U = B22 μ0 Al   

Because Al is the volume of the solenoid, the energy stored per unit volume in the magnetic field surrounding the inductor is

    uBUA l

⇒  uBB22 μ0


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26.

Mutual inductance M between two concentric coils of radii 1 m and 2 m is

  • μ0 π2

  • μ0 π4

  • μ0 π8

  • μ0 π10


27.

Which of the following subsances magnetic susceptibility χm is negative?

  • Diamagnetic

  • Paramagnetic

  • Ferromagnetic

  • antiferromagnetic


28.

When orientation. of dipoles parallel and antiparallel to magnetic field is distributed unequally, then the material is

  • paramagnetic

  • ferromagnetic

  • ferrimagnetic

  • antiferromagnetic


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29.

Lenz law is consistent with conservation of

  • Energy

  • Mass

  • Charge

  • Momentum


30.

Magnetic field at ' 𝑎' distance a from long currying current wire is proportional to

  • 1𝑎

  • 1𝑎2

  • 1𝑎

  • 1𝑎32


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