Question

A physics student has a single-occupancy dorm room. The student has a small refrigerator that runs with a current 3.5 A, a lamp that contains a 100-W bulb, an overhead light with a 60-W bulb, and various other small devices adding up to 3 W. All the appliances run on a voltage of 110 V.

a. What is the total power used by the dorm room (while the refrigerator runs)?  

( )W

b. Assuming that the power plant for the electricity is 14 km away and uses 0000-gauge copper wire (diameter 11.684 mm), how much power is dissipated in transmission (remember to count the return wire), if the power plant is directly providing the 110-V? (To be more precise, the power plant is providing the voltage it needs to provide, so that the voltage at the dorm room is 110 V.)

( )W

c. The most common way to increase the efficiency of power transmission is by using higher voltage for long-distance transmission (and it is "down transformed" nearer the consumers of electricity). Assuming that the same amount of power calculated in (a) is transmitted, how much power is dissipated in transmission, if the power plant provides the power at 110 kV? (To be more precise, the power plant is providing the voltage it needs to provide, so that the voltage at the transformer station is 110 kV.)

( ) W

Answer 1