Electricity

A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R’, then the ratio R/R is –

1. 1/25
2. 1/5
3. 5
4. 25

Solution:

When a wire of resistance R is cut into five equal parts. The resistance of each part is R/5. Let it be ‘r’. When all these five wires are connected in parallel, the resistance of the combination is given by,