Which of the following is constructed on the principle of electromagnetic induction?

In an $L-R$ circuit connected to a battery,the rate at which energy is stored in the inductor is plotted against time during the growth of the current in the circuit. Which of the following best represents the resulting curve?

Two metallic rings $A$ and $B$,identical in shape and size but having different resistivities $\rho_A$ and $\rho_B$,are kept on top of two identical solenoids as shown in the figure. When current $I$ is switched on in both the solenoids in an identical manner,the rings $A$ and $B$ jump to heights $h_A$ and $h_B$,respectively,with $h_A > h_B$. The possible relation$(s)$ between their resistivities and their masses $m_A$ and $m_B$ is(are):
$(A)$ $\rho_A > \rho_B$ and $m_A = m_B$
$(B)$ $\rho_A < \rho_B$ and $m_A = m_B$
$(C)$ $\rho_A > \rho_B$ and $m_A > m_B$
$(D)$ $\rho_A < \rho_B$ and $m_A < m_B$

$A$ square coil $ABCD$ is placed in the $x-y$ plane with its centre at the origin. $A$ long straight wire,passing through the origin,carries a current in the negative $z$-direction. The current in this wire increases with time. The induced current in the coil is:

Consider the conducting square loop shown in the figure. If the switch is closed and after some time it is opened again,then the square loop will show:

The figure shows a planar conductor located in a magnetic field directed inward,normal to the plane of the figure. The magnetic field starts diminishing. Then the induced current: