PCBWay

Q 1. A 68 Ω resistor is connected across the terminals of a 3 V battery. The power dissipation of the resistor is

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(A) 132 mW
(B) 13.2 mW
(C) 22.6 mW
(D) 226 mW

Answer: Option A

Q 2. Energy is equal to power multiplied by voltage.

(A) True
(B) False

Answer: Option B

Q 3. A 120 Ω resistor must carry a maximum current of 25 mA. Its rating should be at least

(A) 4.8 W
(B) 150 mW
(C) 15 mW
(D) 480 mW

Answer: Option B

Q 4. When the pointer of an analog ohmmeter reads close to zero, the resistor being measured is

(A) Overheated
(B) Shorted
(C) Open
(D) Reversed

Answer: Option B

Q 5. The joule is a unit of energy.

(A) True
(B) False

Answer: Option A

Q 6. In 40 kW, there are

(A) 0.4 mW
(B) 40,000 W
(C) 400 W
(D) 5,000 W

Answer: Option B

Q 7. How much continuous current can be drawn from a 60 Ah battery for 14 h?

(A) 42.8 A
(B) 428 A
(C) 4.28 A
(D) 4.2 A

Answer: Option C

Q 8. The watt is the unit of power.

(A) True
(B) False

Answer: Option A

Q 9. A certain appliance uses 350 W. If it is allowed to run continuously for 24 days, how many kilowatt-hours of energy does it consume?

(A) 20.16 kWh
(B) 201.6 kWh
(C) 2.01 kWh
(D) 8.4 kWh

Answer: Option B

Q 10. For 12 V and 40 mA, the power is

(A) 480 mW
(B) 0.480 W
(C) 480,000 µW
(D) All of the above

Answer: Option D

Q 11. A half-watt is equal to how many milliwatts?

(A) 5,000 mW
(B) 5 mW
(C) 500 mW
(D) 50 mW

Answer: Option C

Q 12. A 75 Ω load uses 2 W of power. The output voltage of the power supply is approximately

(A) 120 V
(B) 1.2 V
(C) 12 V
(D) 6 V

Answer: Option C

Q 13. A resistor normally opens when it burns out.

(A) True
(B) False

Answer: Option A

Q 14. The power rating of a carbon-composition resistor that is to handle up to 1.2 W should be

(A) 2 W
(B) 1 W
(C) 5 W
(D) 0.5 W

Answer: Option A

Q 15. The capacity of a battery is measured in milli-amperes.

(A) True
(B) False

Answer: Option B

Q 16. A 33 Ω half-watt resistor and a 330 Ω half-watt resistor are connected across a 12 V source. Which one(s) will overheat?

(A) 33 Ω
(B) 330 Ω
(C) Both resistors
(D) Neither resistor

Answer: Option D

Q 17. A given power supply is capable of providing 6 A for 3.5 h. Its ampere-hour rating is

(A) 0.58 Ah
(B) 2.1 Ah
(C) 21 Ah
(D) 58 Ah

Answer: Option C

Q 18. A battery is one type of power supply that converts chemical energy into electrical energy.

(A) True
(B) False

Answer: Option A

Q 19. If it takes 400 ms to use 12,000 J of energy, the power is

(A) 30 kW
(B) 30 W
(C) 3 W
(D) 300 kW

Answer: Option A

Q 20. Three hundred joules of energy are consumed in 15 s. The power is

(A) 2,000 W
(B) 2 W
(C) 20 W
(D) 200 W

Answer: Option C

Q 21. A power supply produces a 0.6 W output with an input of 0.7 W. Its percentage of efficiency is

(A) 8.57 %
(B) 42.85 %
(C) 4.28 %
(D) 85.7 %

Answer: Option D

Q 22. A 15 V source is connected across a 12 Ω resistor. How much energy is used in three minutes?

(A) 938 Wh
(B) 0.938 Wh
(C) 56.25 Wh
(D) 5.6 Wh

Answer: Option B

Q 23. If you used 400 W of power for 30 h, you have used

(A) 1.3 kWh
(B) 13.3 kWh
(C) 1.2 kWh
(D) 12 kWh

Answer: Option D

Q 24. How many watt-hours represent 65 W used for 18 h?

(A) 11.7 Wh
(B) 1,170 Wh
(C) 11,700 Wh
(D) 117,000 Wh

Answer: Option B

Q 25. A 220 Ω resistor dissipates 3 W. The voltage is

(A) 73.3 V
(B) 2.5 V
(C) 25.7 V
(D) 257 V

Answer: Option C

Q 26. A 6 V battery is connected to a 300 Ω load. Under these conditions, it is rated at 40 Ah. How long can it supply current to the load?

(A) 1 h
(B) 200 h
(C) 2,000 h
(D) 10 h

Answer: Option C

Q 27. A 3.3 kΩ resistor dissipates 0.25 W. The current is

(A) 8.7 mA
(B) 87 mA
(C) 8.7 µA
(D) 8.7 A

Answer: Option A

Q 28. When the current through a 12 kΩ resistor is 8 mA, the power is

(A) 7.68 mW
(B) 768 mW
(C) 7.68 W
(D) 76.8 W

Answer: Option B

Q 29. Watt’s law states the relationships of power to energy.

(A) True
(B) False

Answer: Option B

Q 30. In 0.025 W, there are

(A) 25 kW
(B) 0.00025 mW
(C) 2,500 µW
(D) 25 mW

Answer: Option D

Q 31. Energy equals power multiplied by time.

(A) True
(B) False

Answer: Option A

Q 32. At the end of a 14 day period, your utility bill shows that you have used 18 kWh. What is your average daily power?

(A) 1.286 kWh
(B) 12.85 kWh
(C) 535 kWh
(D) 252 kWh

Answer: Option A

Q 33. The power rating of a resistor determines the minimum power that it can handle safely.

(A) True
(B) False

Answer: Option B

Q 34. If you used 600 W of power for 60 h, you have used

(A) 36 kWh
(B) 3.6 kWh
(C) 10 kWh
(D) 1 kWh

Answer: Option A

Q 35. Power rating is related to resistance value.

(A) True
(B) False

Answer: Option B