In her bathroom, Mindy has an overhead heater that consists of a coiled wire made of nichrome that gets hot when turned on. The wire has a length of 2.3 m when it is uncoiled. The heating element is attached to the normal 120-V wiring and when the wire is glowing red hot it has a temperature of about 439° C and dissipates 2210 W of power. Nichrome has a resistivity of 1.08 10-6 m at 20° C and a temperature coefficient of resistivity of 0.00040° C ?1.
(a) What is the resistance of the heater when it is turned on?
--------?
(b) What current does the wire carry?
--------- A
(c) If the wire has a circular cross section, what is its diameter? Ignore the small changes in the wire's diameter and length due to changes in temperature.
---------- m
(d) When the heater is first turned on, it has not yet heated up, so it is operating at 20° C. What is the current through the wire when it is first turned on?
---------- A