Whenever the magnetic field through a coil is changed,a potential difference is produced in the coil.

What is meant by electromagnetic induction? State the rule which helps in determining the direction of induced current.

The magnetic field produced by a current in a straight wire has no poles.

$A$ uniform magnetic field is directed vertically upwards. In which direction should an $\alpha$-particle (which is a positively charged particle) be projected in this field so that it is deflected southwards? Name and state the rule used to find the direction in this case.

$(a)$ State the function of a fuse in an electric circuit. How is it connected in the domestic circuit?
$(b)$ An electric fuse of rating $3 \, A$ is connected in a circuit in which an electric iron of power $1.5 \, kW$ is connected,which operates at $220 \, V$. What would happen? Explain.

If the key in the arrangement (Figure) is taken out (the circuit is made open) and magnetic field lines are drawn over the horizontal plane $ABCD$,the lines are