What is the role of the two conducting stationary brushes in a simple electric motor?

$(a)$ $A$ coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is:
$(i)$ pushed into the coil with its north pole entering first?
$(ii)$ withdrawn from inside the coil?
$(iii)$ held stationary inside the coil?
$(b)$ Name the above phenomenon and mention the name of the scientist who discovered it. State the law that relates the direction of current in the coil with the direction of motion of the magnet.

Inside a current carrying solenoid,the magnetic field lines are:

Explain what is short circuiting and overloading in an electric supply.

How many times does an $AC$ electric current with the frequency $50\, Hz$ change its direction in one second?

Which of the following appliances cannot be connected in a $15\, A$ current line?