$A$ fuse is a $.......$ wire.

$(a)$ When do we state that an electrical appliance is earthed? Mention the function of the earth wire in electric lines. Why is it necessary to earth electric appliances having a metallic body?
$(b)$ Explain what is short-circuiting and overloading in an electric supply.

The magnetic field at the center of a circular loop carrying an electric current is inversely proportional to $..........$.

State the direction of the magnetic field inside the bar magnet.

Draw the pattern of magnetic field lines associated with a current-carrying straight conductor. State how the magnetic field produced changes:
$(i)$ with an increase in current in the conductor,and
$(ii)$ with an increase in the distance from the conductor.

$(a)$ Describe an activity to determine the direction of magnetic field produced by a current-carrying straight conductor. Also,show that the direction of the magnetic field is reversed on reversing the direction of current.
$(b)$ An $\alpha$-particle (which is a positively charged particle) enters a uniform magnetic field at right angles to it as shown below. Stating the relevant principle,explain in which direction will this $\alpha$-particle move?