Current electricity

Question

1.The resistance of a copper wire of length 5m is 0.5 Q.If the diameter of the wire is 0.05 cm, determine its specific resistance.

2.The resistance of a nichrome wire at 0°C is 100.lf its temperature coefficient

of resistance is 0.004/0C, find its resistance at boiling point of water. Comment on the result.

Answer 1

R = ρˆL/ A

R= Resistance , ρ = Specific Resistance , L = Length , A = cross sectional area = ∏ * r² , Where r = radius of wire

0.5 = ρ *5 / ∏* (0.025* 10 ^-2 ) ²

You get

ρ = Specific Resistance = 1.96*10 ^-8 Ohm *m

R_t = R₀ ( 1+ ∝ t)

Given Resistance at 0⁰C = 100 Ohm

R ₁₀₀ = 100 ( 1+ 0.004* 100)

R₁₀₀ = 100( 1.04) = 104 Ohm = Resistance at 100⁰C ( Boiling point of water)