The temperature coefficients of resistivity in Table 27.1 were determined at a temperature of 20°C. What would they be at 0°C? Note that the temperature coefficient of resistivity at 20°C satisfies p = p0 [1 + a (T - T0)], where p0 is the resistivity of the material at T0 = 20°C. The temperature coefficient of resistivity -3 at 0°C must satisfy the expression p = p0 [+, -3T], where %30 is the resistivity of the material at 0°C.