When a straight wire is heated, its resistance is given by R = R0 [1 + a (T - T0)] according to Equation 27.21, where - is the temperature coefficient of resistivity.
(a) Show that a more precise result, one that includes the fact that the length and area of the wire change when heated, is where -3 is the coefficient of linear expansion.
(b) Compare these two results for a 2.00-m-long copper wire of radius 0.100 mm, first at 20.0°C and then heated to 100.0°C.