Repeat Example 20.3, but for a wire made of silver and given there is one free electron per silver atom.
Example 20.3 Calculate the drift velocity of electrons in a 12-gauge copper wire (which has a diameter of 2.053 mm) carrying a 20.0-A current, given that there is one free electron per copper atom. (Household wiring often contains 12-gauge copper wire, and the maximum current allowed in such wire is usually 20 A.)
(a) Redo Example 20.6 taking into account the thermal expansion of the tungsten filament. You may assume a thermal expansion coefficient of . (b) By what percentage does your answer differ from that in the example?
Example 20.6: Although caution must be used in applying and for temperature changes greater than , for tungsten the equations work reasonably well for very large temperature changes. What, then, is the resistance of the tungsten filament in the previous example if its temperature is increased from room temperature ( ) to a typical operating temperature of ?
Example 20.5: A car headlight filament is made of tungsten and has a cold resistance of . If the filament is a cylinder 4.00 cm long (it may be coiled to save space), what is its diameter? Solution: