Question

Assertion Force constant, $k=\frac{Y A}{l}$, where $Y$ is Young's modulus, $A$ is area and $l$ is original length of the given spring.
Reason Force constant in case of a given spring is called spring constant.

• A. If both Assertion and Reason are true and the Reason is correct explanation of the Assertion
• B. If both Assertion and Reason are true but Reason is not correct explanation of the Assertion
• C. If Assertion is true but Reason is false
• D. If Assertion is false but the Reason is true

Answer 1

Answer: (B)

Here, both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
As, $Y=\frac{F}{A} \frac{l}{\Delta l}$
or $\frac{F}{\Delta l}=\frac{Y A}{l}=k$ (as $F=K \cdot \Delta l$ )