Q. On applying a stress of $20 \times 10^{8}N/m^{2}$ the length of a perfectly elastic wire is doubled. Its Young’s modulus will be
A) $40 \times 10^{8}N/m^{2}$
B) $20 \times 10^{8}N/m^{2}$
C) $10 \times 10^{8}N/m^{2}$
D) $5 \times 10^{8}N/m^{2}$
Explanation
(b) Young’s modulus $= \frac{stress}{strain}$
As the length of wire get doubled therefore strain = 1
$\therefore Y = strain = 20 \times 10^{8}N/m^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.