Question

A coil of constantan wire of length 2 m has an area of cross-section of 7 x 10-7 m2. if its resistivity is 49 x 10-8 ω m, find its resistance.

Answer 1

Given:

length = 2 m

Area of cross section = 7 × $10^{-7} m^{2}$

Resistivity = 49 × $10^{-8}$ Siemens per meter

To find:

Resistance = ?

Formula used:

Resistance of the wire is given by,

R = ω $\frac{l}{A}$

Where R is the resistance

ω = resistivity

A = area of cross section

l = length of wire

Solution:

Resistance of the wire is given by,

R = ω $\frac{l}{A}$

Where R is the resistance

ω = resistivity

A = area of cross section

l = length of wire

R = $\frac{49\times 10^{-8} \times 2}{7\times 10^{-7}}$

R = 1.4 $\Omega$

Thus, Resistance of the wire is 1.4 Ohm.