Question

We have four resistors A ,B ,C and D of resistance 4 ohm,8 ohm ,12 ohm and 24 ohm respectively?
1
Lowest resistance which can be obtained by combining these four resistors
2
highest resistance which can be obtained by combining these four resistors​

Answer 1

Explanation:

Given:

Length of wire,l= 3 m

Area of cross-section,A= 1.7 × 10⁻⁶ m²

Resistance of wire,R=  3 × 10⁻²Ω

To Find:

a) What is the formula for resistivity of the wire and what is the unit of it

b) Calculate the resistivity of the wire

Solution:

a) Resistivity ρ of a conductor is given by

$\pink{\underline{\boxed{\bf{\rho=\dfrac{RA}{l}}}}}$

where,

R is the resistance of conductor

A is area of cross-section of wire

l is length of conductor

Unit of resistivity- Ωm

b) Let the resistivity of wire ρ be

So,

$\longrightarrow\rm{\rho=\dfrac{RA}{l}}$

$\longrightarrow\rm{\rho=\dfrac{3\times10^{-2}\times1.7\times10^{-6}}{3}}$

$\longrightarrow\rm\green{\rho=1.7\times10^{-8}\ \Omega m}$

Hence, the resistivity of given wire is 1.7×10⁻⁸Ωm.

Answer 2

Explanation:

We have four resistors A ,B ,C and D of resistance 4 ohm,8 ohm ,12 ohm and 24 ohm respectively?

1

Lowest resistance which can be obtained by combining these four resistors

2

highest resistance which can be obtained by combining these four resistors