Using Lenz's Law
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Q. Consider two parallel, conducting frictionless tracks are kept in gravity free space as shown in the figure. A movable conductor PQ, initially kept at OA, given a velocity 10 ms−1 towards right. If space contains a magnetic field upon the distance moved by conductor PQ from OA line and given by →B=cx(−^k)[c=constant=1 S.I. unit]. The mass of conductor PQ is 1 kg and length of PQ is 1 m. Answer the following questions based on above passage.
- The distance travelled by conductor when its speed is 5 ms−1 is (102)13m
- The heat loss during the time interval t=0 to time t sec, when the speed of conductor is 5 ms−1 is 50 J
- The distance travelled by conductor when its speed is 5 ms−1 is(152)13m
- The heat loss during the time interval t=0 to time t sec, when the speed of conductor is 5 ms−1 is 10 J
Q. The magnetic flux linked with a coil at any instant ‘t’ is given by ϕ=5t3−100t+300, the e.m.f. induced in the coil at t = 2 second is
- 40 V
- 140 V
- – 40 V
- 300 V
Q. A coil having an area A0 is placed in a magnetic field. The field intensity changes from B0 to 4B0 in time interval of ‘t’. The magnitude of emf induced in the coil will be _____.
- A0B0t
- 3A0B0t
- 3B0A0t
- 4B0A0t
Q. Magnetic flux passing through a coil changes with time as, ϕ=10t2+5t+1 where ϕ is in m wb and t in sec. then magnitude of emf at t = 5s is
- 0.105 V
- 0.01V
- 0.205V
- 1.2 V
Q. A current carrying solenoid is approaching a conducting loop as shown in the figure. The direction of induced current as observed by an observer on the other side of the loop will be


- Anticlockwise
- Clockwise
- East
- West
Q. As shown in the figure, P and Q are two coaxial conducting loops separated by some distance. When the switch S is closed, a clockwise current Ip flows in P (as seen by E) and an induced current IQ1 flows in Q. The switch remains closed for a long time. When S is opened, a current IQ2 flows in Q. Then the directions of IQ1 and IQ2 (as seen by E) are


- Respectively anticlockwise and clockwise
- Respectively clockwise and anticlockwise
- Both clockwise
- Both anticlockwise
Q. An electric potential difference will be induced between the ends of the conductor shown in the diagram, when the conductor moves in the direction
- P
- Q
- M
- L
Q. A circular coil of 20cm2 area is made of 100 turns as shown is figure. In 0.2 sec of time, →B reverses its direction of the field. How much charge flows through wire, if R = 6 Ω?


- 0.16 C
- 0.32 C
- 0.28 C
- 0.64 C
Q. A loop (circuit) is placed in uniform →B & flux through the loop is given by ϕ=4t. Find the power supplied to the 6 volt battery.


- 6 Watt
- 2 Watt
- 3 Watt
- 5 Watt
Q. BAR magnet is moving along the axis of a loop & towards it as shown in the figure.


- VA−VB is negative
- VA−VB is positive
- VA−VB is zero
- No current in the loop