Question 1
An aluminum wire of cross-sectional area 4.0 mm2 is carrying a current of 8.0 A. The density of aluminum is 2.7 g/cm3, and its molar mass is 27 g. Assuming one free electron per aluminum atom, what is the drift speed of the electrons in this wire?
Question 2
The heating coil of a hot water heater has a resistance of 20 ohms and operates at 210 V. If electrical energy costs 5.5 cents per kW-hr, what does it cost to raise the 200 kg of water in the tank from 15°C to 80°C? (The specific heat of water is 4 186 J/kg°C)