. A 150 Ω resistor is connected to a variable-voltage power supply.
a) What voltage is necessary to cause a current of 0.3 A in the resistor? 10 pts
b) What current flows in the resistor when the voltage is 18 V? (This is problem 10 from ch 7 in the textbook.) 10 pts
- A common three-way bulb has two filaments and is wired with three contacts in its base. When used in a three-way lamp, the switch successively sends current first through a high-resistance filament to produce a dim bulb, then through a lower resistance filament to yield a brighter bulb, and finally through both filaments to give the highest brightness bulb.
a) If a particular three-way bulb is rated at 40-, 60-, and 100-watts power and is operated as part of a circuit delivering 120 V, how much current is drawn by the light fixture when used on each of the three possible power/brightness settings? 10 pts
b) If the bulb is left on for 90 minutes in the second switch position, how much energy, measured in both joules and kilowatt-hours, does it consume? If the local cost of electrical energy is $0.08 per kWh, how much does it cost the homeowner to run the lamp for this period of time? (This is problem 28 from chapter 7 in the textbook.) 10 pts