Force and torque on current loop | Learn Physics

10 Question-answer on force and torque on current loop

1.       A straight wire of length 1.0 m and carrying current of 1.2 A is placed in a uniform magnetic field of induction 2T. the magnetic field is perpendicular to the length of wire. The force on the wire is:

(a)    2N

(b)   1.2 N

(c)    3 N

(d)   2.4 N

Ans: ( d)

2.       A wire of length l in formed into a circular loop of one turn only and is suspended in a magnetic field B. when a current I is passed through the loop, the torque experienced by it is:

(a)    (1/4π)BIl

(b)   (1/4π)BIl²

(c)    (1/4π)B² Il

(d)   (1/4π)BI² l

Ans: ( b)

3.       A circular loop of area 0.02 m² carrying a current of 10A, is held with its plane perpendicular to a magnetic field induction 0.2 T. the torque acting on the loop is:

(a)    0.01 Nm

(b)   0.001 Nm

(c)    Zero

(d)   0.8 Nm.

Ans: (c)

4.       To parallel wires carrying currents in the same direction attract each other because of

(a)    Mutual inductance between them

(b)   Potential difference between them

(c)    Electric forces between them

(d)   Magnetic forces between them

Ans: ( d)

5.       Two free parallel wires carrying currents in the opposite directions:

(a)    Attract each other

(b)   Repel each other

(c)    Neither ‘b’ nor ‘c’

(d)   Nothing can be said.

Ans: ( b)

6.       If the distance between two current carrying wires is doubled the force between them becomes:

(a)    4 times

(b)   2 times

(c)    ½ times

(d)   ¼ times

Ans: (c)

7.       The current in wire is directed towards east and the wire is placed in magnetic field directed towards north. The force on the wire is:

(a)    Vertically upwards

(b)   Vertically downwards

(c)    Due south

(d)   Due east.

Ans: (a)

8.       If a coil carrying an electric current is placed in a uniform magnetic field, then

(a)    E.m.f. is produced

(b)   Torque is produced

(c)    Both ‘a’ and ‘b’

(d)   Torque is not produced.

Ans: ( c)

9.       A current carrying conductor, placed in a uniform magnetic field, experiences:

(a)    A mechanical push on it

(b)   An electrostatic imbalance

(c)    A strong force

(d)   A weak force.

Ans: ( a)

10.       If two streams of protons move parallel to each other in the same direction, then these

(a)    Do not exert any force on one another

(b)   Repel each other

(c)    Attract each other

(d)   Get rotated to be perpendicular to each other.

Ans: ( b)