Question

Assertion : Current `I` is flowing through a cylindrical wire of non-uniform cross-section as shown. Section of wire near `A` will be more heated compared to the section near B.
Reason : Current density near `A` is more.
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 the correct explanation of Assertion.
C. If Assertion is true, but the Reason is false.
D. If Assertion is false but the Reason is true.

Answer 1

Correct Answer - B
`R=(rhol)/Aor R/l=` resistance per unit length `=rho/Aprop1/A`
Near `A`, areas of cross section is less. Therefore, resistance per unit length will be more. Hence from the equation `H=i^2Rt`, heat generation near A will be more.
Current density `J=i/A` or `Jprop1/A` (as i is same)`