Question

Four copper wires are given as shown below. Which among these will produce maximum heat when connected to power supply?​
(Here A and L represent the cross-sectional area and the length of the wire respectively.)

• A. Wire Q
• B. Wire P
• C. Wire S
• D. Wire R

Answer 1

The correct option is C Wire S

The heating effect of electric current depends on the material of the wire, length of the wire, and thickness of the wire. Here all wires are made up of the same material, i.e. copper. So, the variation of heating effect with respect to length and thickness is as follows:
(i) Length of the wire: Long wire will get more heated because of the fact that longer the wire, more will be the hindrance to the electric current passing through it.
(ii) Thickness of the wire: Thick wire or wire having more cross-sectional area will make it easier for electric current to pass through it. Therefore, thicker wire will get less heated as compared to the thinner wire.
The wire having a length of 9 mm and a cross-sectional area of 2 $m{m}^2$ is the longest and has the minimum cross-sectional area. Thus, heat generation will be maximum in wire S.