A  coil  of  wire  of  a  certain  radius  has  100 turns and  self  inductance  of  15  mH.  The  self  inductance  of  a  second  of  a  second  similar  coil  of  500  turns  will be

• 75 mH

• 375 mH

• 15 mH

• none of these

Assertion:  Transformers  are  used  only  in  alternating current  source  not  in  direct current. 

Reason: Only  a.c.  can  be  stepped  up  or  down
by  means  of  transformers.

• 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:  A spark occur when the poles of a switch when the switch is opened.

Reason: Current flowing in the conductor produces magnetic field.

• 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 correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

Assertion:  Inductance  coils  are  usually  made  of  thick copper wire. 

Reason:  Induced  current  is more  in  wire  having  less  resistance.

• 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

With the decrease of current in the primary coil from 2 amperes to zero value in  0.01s  the emf generated in the secondary coil is   1000 volts. The mutual inductance of the two coils is

• 1.25 H

• 2.50 H

• 5.00 H

• 10.00 H

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

107.

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