Fundamental property of a type of superconducting material is that $\overrightarrow{B}=0$ everywhere inside it. If a sample of the material is placed into an externally produced magnetic field or is cooled to become superconducting while it is in a magnetic field, electric currents appears on the surface of the sample. The current have precisely the strength and orientation required to make the total magnetic field be zero throughout interior of the sample. Length of solenoid creating field $=l$, total no. of turns $=N$, Area of solenoid $=A$.

A copper ring having a cut such that it does not form a complete loop is held horizontally and a bar magnet is dropped through the ring with its length along the axis of the ring. Then acceleration of the falling magnet is

Two bar magnets A and B, and a non-magnetic bar $\mathrm{C}$, all of same mass and dimensions, are dropped in an identical manner one by one through the center of a copper loop held horizontally (as shown in the figure). The times taken by the bars $A, B$, and $C$ to reach the ground are $t_A,t_B$, and $t_C$, respectively. Which of the following relations is correct?

Lenz's law is in accordance with the law of:

A bar magnet is passing through a conducting loop of radius $R$ with velocity $v.$ The radius of the bar magnet is such that it just passes through the loop. The induced e.m.f. in the loop can be represented by the approximate curve:

Ajay and his friends went for a walk. There they saw a metallic chain attached to a truck touching the ground. It was also written on the truck, “beware highly inflammable". Ajay explained to his friends that during motion of truck, magnetic lines of the earth are cut by its axle and due to this some e.m.f. will be induced across its ends. This induced charge is discharging to the earth through this metallic chain and explosive materials are safe. 

Answer the following questions on the basis of the above paragraph : Name and state the law which gives direction of induced current. 
 

A square conducting loop is placed near an infinitely long current-carrying wire with one edge parallel to the wire as shown in the figure. If the current in the straight wire is suddenly halved, which of the following statements will be true?
"The loop will "
 

The diagram below shows two circular loops of wire $A$ and $B$ centered on and perpendicular to the $x$-axis, and oriented with their planes parallel to each other. The $y$-axis passes vertically through loop $A$ (dashed line). There is a current $I_B$ in loop $B$ as shown. Possible actions which we might perform on loop $A$ are

(i) Move $A$ to the right along $x$-axis closer to $B$.
(ii) Move $A$ to the left along $x$-axis away from $B$.
(iii) As viewed from above, rotate $A$ clockwise about $y$-axis.
(iv) As viewed from above, rotate $A$ anticlockwise about $y$-axis Which of these actions will induce a current in $A$ only in the direction shown.