A current carrying loop is placed in a uniform magnetic field. The torque acting on it does not depend upon

• area of loop

• value of current

• magnetic field

• None of these

A moving coil galvanometer can be converted into an ammeter by

• introducing a shunt resistance of large value in series.

• introducing a shunt resistance of small value in parallel.

• introducing a resistance of small value in series.

• introducing a resistance of large value in parallel.

A charged particle is moving in a cyclotron, what effect on the radius of path of this charged particle will occur when the frequency of the ratio frequency field is doubled?

• It will also be doubled.

• It will be halved.

• It will be increased by four times

• It will remain unchanged.

in a cyclotron , a charged particle

• undergoes acceleration all the time

• speeds up between the Dees because of magnetic field

• speeds up in a Dee.

• slow down within a Dee and speeds up between Dees.

Ampere’s circuital law is given by

• a

• b

• c

• d

Current sensitivity of a galvanometer can be increased by decreasing :

• Magnetic field B

• number of turns N

• torsional constant K

• Area A

A wire in the form of a circular loop, of one turn carrying a current, produces magnetic

induction B at the centre. If the same wire is looped into a coil of two turns and carries the

same current, the new value of magnetic induction at the centre is

• B

• 2 B

• 4 B

• 8 B

A solenoid has 1000 turns per metre length. If a current of 5A is flowing through it, then magnetic field inside the solenoid is

• 2 PIE 10-3 T

• 2 PIE 10-5 T

• 4 PIE 10-3 T

• 4 PIE 10-5 T

Currents of 10 A and 2 A are flowing in opposite directions through two parallel wires A and

B respectively. If the wire A is infinitely long and wire B is 2 m long, then force on wire B

which is situated at 10 cm from A, is

• 8 X 10-5 N

• 6 X 10-5 N

• 4 X 10-5 N

• 2 X 10-5 N

The magnetic effects of electric current was discovered by

• Ampere

• Oersted

• Fleming

• Faraday