Question

Assertion :When radius of a circular loop carrying current is doubled, its magnetic moment becomes four times. Reason: Magnetic moment depends on the area of the loop.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
• C. Assertion is correct but Reason is incorrect
• D. Assertion is incorrect but Reason is correct

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

Area $A=\pi r^2$
Area after radius is doubled $A^{\prime }=\pi (2r{)}^2=\pi (4r^2)$
Since $\mu \propto A$, ${\mu }^{\prime }=4\mu$