ELECTROMAGNETIC INDUCTION

Which of the following gives the direction of the induced e.m.f.?

• Faraday’s law

• Lenz’s law

• Ampere

• Biot-Savart’s law.

Which of the following is/are equal to Henry?

• Volt second/ampere.

• Volt(second)²/coulomb.

• Joule (second)²/(coulomb)²

• All of these

A coil of metal wire is kept stationary in a non-uniform magnetic field:

• An e.m.f. and current both are induced in the coil.

• An e.m.f. but not the current is induced iii the coil.

• Current but not the e.m.f is induced in the coil.

• Neither e.m.f. nor current is induced in the coil.

When the rate of change of current through a closed circuit is unity, then the induced e.m.f. produced in it is equal to

• Voltage

• Coefficient of self induction or self inductance L.

• Electric field

• Current

Which of the following is most suitable for the core of electromagnets 

• Soft iron  

• Soft iron 

• SteelCopper-nickel alloy  

• Air

Identify the paramagnetic substance 

•     Iron 

•   Aluminium

• Nickel     

• Hydrogen

A diamagnetic material in a magnetic field moves

• From weaker to the stronger parts of the field

• Perpendicular to the field

• From stronger to the weaker parts of the field

• In none of the above directions

A square of side L meters lies in the x-y plane in a region where the magnetic field is given by B=B0 (2i^+3j^+4k^) Testa, where B0 is constant. The magnitude of flux passing through the square is

• 2B0L²Wb

  
  

• 3B0L²Wb

• 4B0L²Wb

• √29 B0L2Wb

There are two coils A and B as shown in figure. A current starts flowing in B as shown, when A is moved towards B and stops when A stops moving. The current in A is counter clockwise. B is kept stationary when A moves. We can infer that

• there is a constant current in the clockwise direction in A.

• there is a varying current in A.

• there is no current in A.

• there is a constant current in the counter clockwise direction in A.

The magnetic flux linked with a coil is given by an equation

ϕ=5t²+2t+3

. The induced e.m.f. in the coil at the third second will be

• 32 units

• 54 units

• 40 units

• 65 units