A resistor of 80 2 resistance, having a temperature coefficient of 0.0021 per C is to be constructed. Wires of two materials of suitable cross-sectional area are available. For material A, the resistance is 80 per 100 metres and the temperature coefficient is 0.003 per C. For material B, the corresponding figures are 60 per metre and 0.0015 per C. Calculate suitable lengths of wires of materials A and B to be connected in series to construct the required resistor. All data are referred to the same temperature. B A www www