Question

Figure shows the strain-stress curve of two metals $P$ and $Q$.

• A. $P$ has greater young's modulus
• B. $Q$ has greater young's modulus
• C. $P$ and $Q$ have same young's modulus
• D. None of these

Answer 1

The correct option is A $P$ has greater young's modulus

We know that,
Young's modulus $=\frac{\text{stress}}{\text{strain}}$ ... (1)
Slope of the curve,
$\tan \theta =\frac{\text{strain}}{\text{stress}}$ ... (2)


From (1) and (2),
Young's modulus $=\frac{1}{\tan \theta }$
So, lower the value of $\theta$, higher the Young's modulus.
From figure, we can see that ${\theta }_1<{\theta }_2\Rightarrow \tan {\theta }_1<\tan {\theta }_2$
$\Rightarrow Y_P>Y_Q$
Metal $P$ has greater Young's modulus.