Question

A copper wire has a diameter of 0.5mm and resistivity 1.6*10^-8ohm m.

1) what will be the length of this wire to make the resistance of 12 ohm?

2) how much will be the resistance of another copper wire of the same length but half the diameter?
Pls reply soon​

Answer 1

Given:

Diameter = d = 0.5 mm

Resistivity, ρ = 1.6×10  −8 Ω

Resistance, R = 12 Ω

To Find:

Length of the wire

Solution:

A = πd²/4

R = ρl/A

= pl/ πd²/4

Therefore,

l = Rπd²/4p

l = 12 × 3.14 × (0.5 × 10`-3)² / 4 ×  1.6×10  −8

= 1.472

Thus, If the diameter is doubled, resistance will be one-fourth.

Answer: The length of the wire is 1.472m

Answer 2

Explanation:

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