Q. Consider a rectangular slab of length $L$ and area of cross section $A.$ A current $I$ is passed through it. If the length is doubled, the potential drop across the end faces
A) Becomes half of the initial value
B) Becomes one-fourth of the initial value
C) Becomes double the initial value
D) Remains same
Explanation
(c) Resistance of the slab $= \rho\frac{L}{A}$ where
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The potential across $R$ is $I \times R = V$
The length of the slab is doubled. Therefore the resistance is $2R.$ Assuming that the same current is passed, the potential across the new resistance is $l \times 2R = 2V$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.