Electromagnetic Induction

Assertion: : A current continues to follow in superconducting coil even after switch is off.

Reason: Superconducting coils show Meissner effect.

• 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

Assertion: An emf  $\overline{\mathrm{E}}· \overline{\mathrm{dl}}$  is induced in a closed loop where magnetic flux is varied. The induced E is not a conservative field. 

Reason:  The line integral $\overline{\mathrm{E}}·\overline{\mathrm{dl}}$ around the closed loop is non-zero.

• 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

ASsertion:- A larger dry cell has higher emf.

Reason:-  The emf of a dry cell is proportional to its size.

• 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

Figure shown is a distribution of charges. The flux of electric field due to these charges through the surface S is

• $\frac{3\mathrm{q}}{{\mathrm{\epsilon }}_{\mathrm{o}}}$

• $\frac{2\mathrm{q}}{{\mathrm{\epsilon }}_{\mathrm{o}}}$

• $\frac{\mathrm{q}}{{\mathrm{\epsilon }}_{\mathrm{o}}}$

• zero

Assertion:  We use a thick wire in the secondary of a step down transformer to reduce the production heat. 

Reason:  When the plane of the armature is parallel to the line of force of magnetic field, the magnitude of induced e.m.f. is maximum.

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

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

• If the assertion is true but the reason is false.

• If both assertion and reason are false

If electron is moving from A to B in wire AB, then current induced in the coil is

• anticlockwise

• clockwise

• arbitrary direction

• no current will be induced

A 100 mH coil carries a current of 1 A. The energy stored in the magnetic field is

• 0.1 J

• 0.05 J

• 0.5 J

• 1 J

The mutual inductance of an induction coil is 5 H. In the primary coil, the current reduces from 5 A to zero is ${10}^{-3}$s What is the induced emf in the secondary coil?

• 2500 V

• 25000 V

• 2510 V

• Zero

Two coils of self-inductance L₁ and L₂ are placed so close together that effective flux in one coil is completely linked with the other. If M is the mutual inductance between them, then

• M = L₁L₂

• M = L_1/L₂

• M = L

• $\mathrm{M} = \sqrt{{\mathrm{L}}_1{\mathrm{L}}_2}$

S.I unit of magnetic flux is :

• tesla

• oersted

• weber

• gauss