Physics
The north pole of a magnet is brought near a metallic ring as shown in the figure given below. The direction of induced current will be :
- anticlockwise
- clockwise
- first anticlockwise and then clockwise
- first clockwise and then anticlockwise
Answer
anticlockwise
Reason — As the north pole of the magnet is brought closer to the metallic ring, the magnetic flux through the ring increases.
According to Lenz’s law, the induced current flows in such a direction as to oppose this increase in flux so to oppose the approaching north pole, the face of the ring towards the magnet must behave like a north pole.
For a circular loop, this happens when the current flows anticlockwise (as seen from the magnet side).
Hence, the direction of induced current will be anticlockwise.
Related Questions
(i) The number of turns in the secondary coil of a transformer is 20 times than that in a primary coil. If the power fed to the primary coil is 100 W (assume no energy loss), then what is the power output at the secondary coil ?
- 5 W
- 100 W
- 2000 W
- 4000 W
(ii) If the primary coil of the above transformer is supplied with 10 V, what is the voltage of the secondary coil ?
- 0.5 V
- 10 V
- 200 V
- 100 V
An electron moves on a straight line path XY as shown. abcd is a coil adjacent to the path of electron. The direction of induced current, if any, in the coil will be :
- No curent is induced
- abcd
- adcb
- No fixed direction
Two thin wires carrying same currents lie on X and Y axis as shown in the figure. The origin of axis is O. The magnetic field will be zero on line :
- AB
- CB
- part OB of line AB
- part OC of line CD
Assertion (A): A current carrying solenoid when suspended freely sets itself in the north-south direction just like a bar magnet.
Reason (R): The end of the solenoid where the direction of current is anti-clockwise behaves as a north pole and the end where the direction of the current is clockwise behaves as a south pole.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true and R is not the correct explanation of A.
- assertion is false but reason is true.
- assertion is true but reason is false.