Physics · PYQ NEET UG 2016(1)
हिन्दीCoefficient of linear expansion of brass and steel rods are \( \alpha_1 \) and \( \alpha_2 \). Lengths of brass and steel rods are \( l_1 \) and \( l_2 \) respectively. If \( (l_2 - l_1) \) is maintained same at all temperatures, which one of the following relations holds good?
Correct answer · Option 1
\( \alpha_1 l_1 = \alpha_2 l_2 \)
Explanation
For \( (l_2 - l_1) \) to remain constant with temperature change \( \Delta T \), the change in lengths must be equal: \( \Delta l_2 = \Delta l_1 \implies l_2 \alpha_2 \Delta T = l_1 \alpha_1 \Delta T \implies \alpha_1 l_1 = \alpha_2 l_2 \).