The figure shows a rectangular block with dim | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(C) Let $\rho$ be the resistivity of the material.The resistance $R$ of a conductor is given by $R = \rho \frac{L}{A}$,where $L$ is the length of the

Vedclass · Accepted Answer

$C-C$

Vedclass · Answer

(C) Let $ho$ be the resistivity of the material.The resistance $R$ of a conductor is given by $R = ho \frac{L}{A}$,where $L$ is the length of the conductor in the direction of current flow and $A$ is the cross-sectional area perpendicular to the current flow.$1$. For contact $A-A$ (Top and bottom faces):The length $L = x$ and the area $A = 2x 	imes 4x = 8x^2$.$R_{AA} = ho \frac{x}{8x^2} = \frac{ho}{8x}$.$2$. For contact $B-B$ (Left and right faces):The length $L = 2x$ and the area $A = x 	imes 4x = 4x^2$.$R_{BB} = ho \frac{2x}{4x^2} = \frac{ho}{2x} = \frac{4ho}{8x}$.$3$. For contact $C-C$ (Front and rear faces):The length $L = 4x$ and the area $A = x 	imes 2x = 2x^2$.$R_{CC} = ho \frac{4x}{2x^2} = \frac{2ho}{x} = \frac{16ho}{8x}$.Comparing the resistances,$R_{CC} > R_{BB} > R_{AA}$.Thus,the maximum electrical resistance is obtained for contact $C-C$.

Similar Questions

$A$ cylindrical metallic wire is stretched to increase its length. If the resistance of the wire is increased by $4 \%$, then the percentage increase in its length is (in $\%$)

The external diameter of a $5 \, m$ long hollow tube is $0.1 \, m$ and the thickness of its wall is $0.005 \, m$. If the resistivity $\rho = 1.7 \times 10^{-8} \, \Omega \cdot m$, then its resistance will be:

The resistance of an incandescent lamp is

If a conducting wire of length $L$ is uniformly stretched to double its length, then its conductivity becomes . . . . . . .

$A$ wire of $1 \,\Omega$ has a length of $1\, m$. It is stretched until its length increases by $25\, \%$. The percentage change in resistance to the nearest integer is .....$\%$

Vedclass Test Series

Exam Paper Generator

Online Exam Module