Question

If the resistance of a coil is 2 Ω at 0°C and α = 0.004 /°C, then its resistance at 100°C is
(a) 1.4 Ω
(b) 0 Ω
(c) 4 Ω
(d) 2.8 Ω

Answer 1

relation between resistance and temperature is given by
R = R₀[1 + α × (T - T₀) ]
Here R is the resistance at temperature T
R₀ is the temperature at temperature T₀
α is the constant

Here, R₀ = 2Ω , T = 100°C , T₀ = 0°C and α = 0.004 /°C
Now, R = 2[1 + 0.004 × (100 -0)]
= 2 [1 + 0.004 × 100]
= 2 [1 + 0.4]
= 2 × 1.4
= 2.8 Ω

Hence , option (d) is correct

Answer 2

Answer:

If the resistance of a coil is 2 Ω at 0°C and α = 0.004 /°C, then its resistance at 100°C is 2.8 Ω