Question

Two wires A and B are connected in series at 0°C and resistance of B is 3.5 times that of A. The resistance temperature coefficient of A is 0.4% and that of the combination is 0.1%. Find the resistance temperature coefficient of B.

Answer 1

A simple technique which gives quick results in such questions is illustrated by the diagram of Fig. 1.9. 

It is seen that 

R_B/R_A = 0.003/(0.001 − α) 

or 3.5 = 0.003/(0.001 − α) 

or α = 0.000143°C−1 or 0.0143 %