In $SI$,Henry is the unit of

The current $I$ in an $A.C.$ circuit inductance coil varies with time according to the graph given below. Which one of the following graphs gives the variation of voltage with time?

The figure shown has two coils of wires placed in close proximity. The current in primary coil $P$ is made to vary with time as shown in the graph. Which of the following graphs best represents the variation of the emf induced in the secondary coil $S$?

Write down the names of two devices which work on the principle of electromagnetic induction.

$A$ small bar magnet is moved through a coil at a constant speed from one end to the other. Which of the following series of observations will be seen on the galvanometer $G$ attached across the coil? Three positions shown describe: $(a)$ the magnet's entry,$(b)$ the magnet is completely inside,and $(c)$ the magnet's exit.

Two long parallel wires whose centres are at a distance $d$ apart carry equal currents in opposite directions. If the flux within the wires is neglected,the inductance of such an arrangement of wire of length $l$ and radius $a$ will be