Question

Two metallic rods are connected in series. Both are of same material of same length and same area of cross-section. If the conductivity of each rod be k, then what will be the conductivity of the combination ?

• A. 4 k
• B. 2 k
• C. k
• D. k/2

Answer 1

Answer: (C)

k

Answer 2

$\frac{2L}{k_{eq.}A}$ = $\frac{L}{kA}$ + $\frac{L}{kA}$

$\frac{2}{k_{eq}.}$ = $\frac{2}{k}$ Ž k_eq. = k

For parallel

k_eq. = $\frac{k_{1}A_{1} + k_{2}A_{2}}{A_{1} + A_{2}}$= k