Question

Consider a conductor of variable cross section in which current is flowing from cross section $1$ to $2$. Then

• A. current passing through both the cross sections is the same.
• B. current through $1$ is less than that through $2$.
• C. drift velocity of electrons at $1$ is less than that at $2$.
• D. drift velocity is same at both the cross sections.

Answer 1

Answer: (A), (C)

drift velocity of electrons at $1$ is less than that at $2$.
current passing through both the cross sections is the same.

As the cross sections are in series, so the current in them will be the same.
We know that drift velocity, $v_d=\frac{I}{neA}$ or $v_d\propto \frac{1}{A}$
As area of cross section 1 is more so drift velocity at 1 is less than at 2.Hence correct options are A and C.