(b) $\frac{Q}{t} = \frac{KA\mathrm{\Delta}\theta}{l} \Rightarrow 6000 = \frac{200 \times 0.75 \times \mathrm{\Delta}\theta}{1}$ $\therefore\ \mathrm{\Delta}\theta = \frac{6000 \times 1}{200 \times 0.75} = 40℃$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.