Bonus Problems Circuits and Power

Bonus Problems – Circuits and Power

1.) It is estimated that in the United States (population 250 million) there is one electric clock per person, with each clock using energy at a rate of 2.5 W. using this estimate, how much energy is consumed by all of the electric clocks in the United States in a year? How much does it cost if energy costs 7 cents per kWh.

2.) An 11.0 W energy-efficient fluorescent lamp is designed to produce the same illumination as a conventional 40.0 W lamp. a.) How much energy does this lamp save during 100.0 h of use? b.) If electrical energy costs 8 cents per kWh, how much money is saved in 100 h?

3.) Use the electric bill shown in the Figure 19-21 to answer the following questions: a.) How many joules of energy were consumed in this billing cycle? b.) What is the average amount of energy consumed per day in joules and kilowatt-hours? c.) If the cost of energy were increased to 15 cents per kWh, how much more would energy cost in this billing cycle?

4.) For the circuit shown in Figure 20-38, determine the following: a.) the current in the 2.0 Ohms resistor. b.) the potential difference across the 2 ohm resistor. c.) the potential difference across the 12 Ohm resistor. d.) the current in the 12 ohm resistor.

5.) The equivalent resistance for the circuit shown in Figure 20-43 drops to one-half its original value when the switch, S, is closed. Determine the value of R. 6.) Four resistors are connected to a battery with a terminal voltage of 12 V, as shown in Figure 20-44. Determine the following: a.) the equivalent resistance for the circuit. b.) the current in the battery c.) the current in the 30 Ohm resistor d.) the power dissipated by the 50 Ohm resistor e.) the power dissipated by the 20 Ohm resistor.

7.) Two resistors, A and B, are connected in series to a 6 V battery. A voltmeter connected across resistor A measures a potential difference of 4 V. When the two resistors are connected in parallel across the 6 V battery, the current in B is found to be 2 A. find the resistances of A and B.

8.) Draw a schematic diagram of nine 100 Ohm resistors arranged in a series-parallel network so that the total resistance of the network is also 100 Ohm. All nine resistors must be used. 9.) The power supplied to the circuit shown in Figure 20-46 is 4 W. Determine the following: a.) the equivalent resistance of the circuit. b.) the potential difference across the battery.