Question

$1 \,Kcal$ of heat flowing through a rod of iron. When the rod is cut down to $4$ pieces then what will be the heat flowing through each piece having same differential temperature?

• A. 1/2 Kcal
• B. 1/4 Kcal
• C. 1 Kcal
• D. 1/15 Kcal

Answer 1

Answer: (C)

1 Kcal

Answer 2

We know that the heat flowing through a conductor is given by $\frac{Q}{t} = -KA \left(\frac{d\theta}{dx}\right)$ $\Rightarrow\,Q = -KA \left(\frac{d\theta}{dx}\right)t$ Where K = thermal conductivity of the material A = area of crosssection $\frac{d\theta}{dx}$ = temperature gradient t = time Now if we cut the rod into 4 pieces, A remains same K remains same, $\frac{d\theta}{dx}$ is said to be same, so forsame time t, Q is going to be same as earlier.