Energy and Power Model Test(1st)

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

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21 Ah
58 Ah
0.58 Ah
2.1 Ah

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

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8.57 %
85.7 %
42.85 %
4.28 %

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

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200 W
2,000 W
20 W
2 W

Watt's law states the relationships of power to energy.

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False
True

A 220 Ω resistor dissipates 3 W. The voltage is

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25.7 V
257 V
73.3 V
2.5 V

For 12 V and 40 mA, the power is

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0.480 W
All of the above
480,000 µW
480 mW

Energy is equal to power multiplied by voltage.

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False
True

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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22.6 mW
226 mW
13.2 mW
132 mW

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

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Shorted
Reversed
Overheated
Open

The watt is the unit of power.

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False
True

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

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1.3 kWh
13.3 kWh
1.2 kWh
12 kWh

A half-watt is equal to how many milliwatts?

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5 mW
50 mW
5,000 mW
500 mW

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

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42.8 A
4.28 A
4.2 A
428 A

The joule is a unit of energy.

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False
True

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

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0.938 Wh
938 Wh
56.25 Wh
5.6 Wh

In 0.025 W, there are

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0.00025 mW
2,500 µW
25 mW
25 kW

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

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True
False

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

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12.85 kWh
252 kWh
535 kWh
1.286 kWh

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

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30 kW
3 W
30 W
300 kW

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

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False
True

A resistor normally opens when it burns out.

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False
True

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

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15 mW
4.8 W
480 mW
150 mW

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?

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200 h
10 h
1 h
2,000 h

A 3.3 kΩ resistor dissipates 0.25 W. The current is

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8.7 µA
87 mA
8.7 mA
8.7 A

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

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1 W
2 W
5 W
0.5 W

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

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12 V
1.2 V
120 V
6 V

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?

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Neither resistor
33 Ω
330 Ω
Both resistors

In 40 kW, there are

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5,000 W
400 W
0.4 mW
40,000 W

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?

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2.01 kWh
8.4 kWh
20.16 kWh
201.6 kWh

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

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117,000 Wh
11.7 Wh
11,700 Wh
1,170 Wh

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

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True
False

Power rating is related to resistance value.

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False
True

Energy equals power multiplied by time.

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False
True

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

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7.68 W
768 mW
7.68 mW
76.8 W

Energy and Power Model Test(1st) : Question 1 of 34