Question

Two wires $A$ and $B$ of the same material, having radii in the ratio $1: 2$ and carry currents in the ratio $4: 1$. The ratio of drift speed of electrons in $A$ and $B$ is

• A. $16: 1$
• B. $1: 16$
• C. $1: 4$
• D. $4: 1$

Answer 1

Answer: (A)

Current flowing through the conductor, $I= nevA$.
Hence $\frac{4}{I}=\frac{n e v_{d_{1}} \pi(1)^{2}}{n e v_{d_{2}} \pi(2)^{2}}$
or $\frac{v_{d_{1}}}{v_{d_{2}}}=\frac{4 \times 1}{1}=\frac{16}{1}$