Question

calculate the resistance of 2m long nichrome wire of radius 0.321mm. resistivity of nichrome is 15×10-6 ohmsm. if the potential difference of 10v is applied across the wire what will be the current in wire

Answer 1

Hi friend!

A = πr² = π(0.321 x 10⁻³)² = 3.24 x 10⁷ 

= 3.24 x 10⁻⁷m²

Now, the resistance per unit LENGTH is r/l 

R /  l = p / a = 1.5 x 10⁻⁶ / 3.24 x 10⁻⁷ = 4.6Ω/m

Now let us find the current in the wire: 

I = V / R 

> 10/4.6

> 2.2 A
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I hope this helps

Answer 2

The current in the wire is 0.11 A.

Explanation:

Given the length of the wire, l = 2 m.

The radius of the wire, r = 0.321 mm =0.000321 m.

Cross-sectional area of the wire, $A=\pi r^2= 3.14\times(0.321\times10^-^3)^2m^2$.

The resistivity of the nichrome wire, $\rho=15\times10^-^6\Omega.m$.

The potential difference,V =10 V.

The resistance of the wire,

$R=\rho\frac{l}{A}$

substitute the values, we get

$R=\frac{15\times10^-^6\Omega.m\times2m}{3.14\times(0.321\times10^-^3)^2m^2}$

$R=92.7\Omega$.

To get current in the wire use ohm`s law (V = iR).

$i=\frac{10V}{92.7\Omega}$

i = 0.107 = 0.11 A.

Thus, the current in the wire is 0.11 A.

#Learn More: ohm`s law.

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