1.Determine the current resulting from the application of a 9 V battery across a network with a resistance of 2.2 Ω.
2. Calculate the resistance of a 60 W bulb if a current of 500 mA results from an applied voltage of 120 V.
3. Calculate the current through the 2 kΩ resistor in Fig. if the voltage drop across it is 16 V.
4. What is the power dissipated by a 5 Ω resistor if the current is 4 A?
5. The I@V characteristics of a light bulb are provided in Fig. Note the nonlinearity of the curve, indicating a wide range in resistance of the bulb with applied voltage. If the rated voltage is 120 V, find the wattage rating of the bulb. Also calculate the resistance of the bulb under rated conditions.
6. Determine the current through a 5 kΩ resistor when the power dissipated by the element is 20 mW.
7. How much energy (in kilowatthours) is required to light a 60 W bulb continuously for 1 year (365 days)?
8. How long can a 340 W plasma TV be on before it uses more than 4 kWh of energy?
9. What is the cost of using a 5 hp motor for 2 h if the rate is 12¢ per kilowatthour?
10. What is the total cost of using all of the following at 12¢ per kilowatthour?
A 1200 W toaster for 30 min
Six 50 W bulbs for 4 h A
500 W washing machine for 45 min A
4300 W electric clothes dryer for 20 min
An 80 W PC for 6 h
11. What is the output in horsepower of a motor with an efficiency of 80% and an input current of 8 A at 120 V?
12. If Effi. = 0.85, determine the output energy level if the applied energy is 50 J.
13. What is the voltage across a 220 Ω resistor if the current through it is 5.6 mA?
14. What is the current through a 2.2 kΩ resistor if the voltage drop across it is 24 V?
15. How much resistance is required to limit the current to 1.5 mA if the potential drop across the resistor is 24 V?
16. At starting, what is the current drain on a 12 V car battery if the resistance of the starting motor is 40 mΩ?
17. If the current through a 200 kΩ resistor is 5.0 mA, what is the voltage drop across the resistor?
18. If a voltmeter has an internal resistance of 50 kΩ, find the current through the meter when it reads 120 V.
19. If a refrigerator draws 2.2 A at 120 V, what is its resistance?
20. If a clock has an internal resistance of 7 kΩ, find the current through the clock if it is plugged into a 110 V outlet.
21. A washing machine is rated at 4.6 A at 150 V. What is its internal resistance?
22. A CD player draws 80 mA when 4.5 V is applied. What is the internal resistance?
23. The input current to a transistor is 30 mA. If the applied (input) voltage is 36 mV, determine the input resistance of the transistor.
24 . The internal resistance of a dc generator is 0.8 Ω. Determine the loss in terminal voltage across this internal resistance if the current is 14 A.
25. If 540 J of energy are absorbed by a resistor in 3.6 min, what is the power delivered to the resistor in watts?
26. The power to a device is 60 joules per second (J/s). How long will it take to deliver 840 J?
27. a. How many joules of energy does a 3 W nightlight dissipate in 12 h? b. How many kilowatthours does it dissipate?
28. How long must a steady current of 1.4 A exist in a resistor that has 3 V across it to dissipate 12 J of energy?
29. What is the power delivered by a 12 V battery if the current drain is 40 A?
30. The current through a 4 kΩ resistor is 7.2 mA. What is the power delivered to the resistor?
31. The power consumed by a 2.2 kΩ resistor is 240 mW. What is the current level through the resistor?
32 . What is the maximum permissible current in a 69 Ω, 2 W resistor? What is the maximum voltage that can be applied across the resistor?
33 . The voltage drop across a transistor network is 22 V. If the total resistance is 16.8 kΩ, what is the current level? What is the power delivered? How much energy is dissipated in 1 h?
34 . If the power applied to a system is 10 kW, what is the voltage across the line if the current is 48 A?
35. A 1.5 W resistor has a resistance of 5.0 MΩ. What is the maximum current level for the resistor? If the wattage rating is increased to 2.5 W, will the current rating double?
36. A 2.2 kΩ resistor in a stereo system dissipates 42 mW of power. What is the voltage across the resistor?
37. What are the “hot” resistance level and current rating of a 240 V, 100 W bulb?
38. What are the internal resistance and voltage rating of a 450 W automatic washer that draws 3.75 A?
39. A calculator with an internal 4.5 V battery draws 0.5 mW when fully functional.
a. What is the current demand from the supply?
b. If the calculator is rated to operate 550 h on the same battery, what is the ampere-hour rating of the battery?
40. A 20 kΩ resistor has a rating of 100 W. What are the maximum current and the maximum voltage that can be applied to the resistor?
41. What is the total horsepower rating of a series of commercial ceiling fans that draw 40 A at 240 V?
42.. A 12 Ω resistor is connected across a 12 V battery.
a. How many joules of energy will it dissipate in 2 min?
b. If the resistor is left connected for 4 min instead of 2 min, will the energy used increase? Will the power dissipation level increase?
43. How much energy in kilowatthours is required to keep a 230 W oil-burner motor running 12 h a week for 5 months? (Use 4 weeks = 1 month.) 39. How long can a 1500 W heater be on before using more than 12 kWh of energy?
44. A 60 W bulb is on for 10 h.
a. What is the energy used in wattseconds?
b. What is the energy dissipated in joules?
c. What is the energy transferred in watthours?
d. How many kilowatthours of energy were dissipated?
