Question

Two pieces of conductor of same material and of equal length are connected in series with a cell. One of the two pieces has cross-sectional area double that of the other. Which one of the following statements is correct in this regard?

• A. The thicker one will allow stronger current to pass through it
• B. The thinner one would allow stronger current to pass through it
• C. Same amount of electric current would pass through both the pieces producing more heat in the thicker one
• D. Same amount of electric current would pass through both the pieces producing more heat in the thinner one

Answer 1

The correct option is D Same amount of electric current would pass through both the pieces producing more heat in the thinner one

Resistance of the wire $R=\frac{\rho l}{A}$
$⟹R\propto \frac{1}{A}$
Since, thinner wire has less cross-sectional area. So it has more resistance than thicker wire.
Also, same current flows the both the pieces of conductor as they are connected in series with each other.
Heat produced $H=I^{2}Rt$
$⟹H\propto R$ for same $I$ and $t$.
Thus option D is correct.