Fill in the blanks:

(a) Longer line in the symbol for a cell represents its [[1]] terminal.

(b) The combination of two or more cells is called a [[2]].

(c) When current is switched ‘on’ in a room heater, it [[3]]. 

(d) The safety device based on the heating effect of electric current is called a [[4]].

a) Ans: Positive

An electric cell is a device, which converts chemical energy into electrical energy. It has two terminals, which are made up of metal: one terminal is positive ( + ), while the other one is negative ( - ). When the two terminals are connected to an electrical device, electric current flows through it.

An electric cell can be represented using the below symbol.

Here the longer line indicates the positive terminal while the smaller line indicates the negative terminal.