### Physics - Electromagnetic induction And Alternating Currents

#### Question - 1

A rectangular loop of width l is placed in a uniform magnetic field $\overrightarrow { B }$, at right angle to the plane of the loop. It is pulled with a force F from side l so that it moves with a uniform velocity $\vartheta$.the ohmic resistance of the loop is R=5 ohm,l=0.10m,B=0.2T, and $\vartheta$=15 cm $??{ s }^{ -1 }$. the current induced in the loop is:

• A 6 mA
• B 6$\mu A$
• C 0.6 mA
• D 60 mA

#### Question - 2

As follows from question 3, the rate of joule heating in the loop is

• A $1.8\times { 10 }^{ -6 }W$
• B $1.8\times { 10 }^{ -4 }W$
• C $1.8\times { 10 }^{ -2 }W$
• D $1.8\times { 10 }^{ -8 }W$

#### Question - 3

A coil of wire is rotated in a uniform magnetic field.

• A A direct current of constant e.m.f is produced
• B An alternating e.m.f of constant amplitude is produced
• C An alternating e.m.f of varying frequency is produced
• D A direct current of varying e.m.f is produced

#### Question - 4

Lenz's law is a consequence of

• A law of conservation of charge
• B law of conservation of energy
• C retarding force and ohm's law
• D magnetic effect of current

#### Question - 5

Two identical coils each of inductance L are equivalent to a total inductance of 2H when connected in parallel.The value of L for each coil is:

• A 1H
• B 2H
• C 4H
• D 6H

#### Question - 6

Three metalic loops of copper,platinum and sliver having exactly the same dimension,are rotating in a uniform magnetic field with the same angular velocity.The induced e.m.f is

• A maximum in copper loop
• B maximum in platinum loop
• C maximum in sliver loop
• D same in all the loops

#### Question - 7

The current through a coil of inductance 2H falls from 5 A to 4 A in one second. The e.m.f developed across the coil is

• A -2V
• B 2V
• C -10V
• D 10V

#### Question - 8

The direction of induced e.m.f can be found by

• A Fleming's left-hand rule and Lenz's law
• B Fleming's right-hand rule
• C Right hand thumb rule
• D Maxwell's cork-screw rule

#### Question - 9

The parallel LC circuit acts as a simple harmonic oscillator due to the exchange of

• A Kinetic and potential energy
• B velocity of positive and negative charge
• C electric and magnetic energy
• D electric energy in C and magnetic energy in L.

#### Question - 10

In a D.C motor the direction of force on the sides of the coil can be found by

• A Fleming's left-hand rule
• B Fleming's right-hand rule
• C SNOW rule
• D Ampere's swiming rule