# X - QUANTITIES AND UNITS

In document Basic Electronics (Page 65-71)

48. What is the difference between common-mode and differential-mode input signals?

A. phase relationship B. voltage

C. current

D. apparent power

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49. A circuit that uses an amplifier with passive filter elements is called a(n):

A. relaxation oscillator B. signal generator C. differential amplifier D. active filter

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50. The input offset current equals the A. average of two base currents

B. collector current divided by the current gain C. difference between two base-emitter voltages

D. difference between two base currents

X - QUANTITIES AND UNITS

1. Derived units are obtained from various combinations of A. electrical quantities

B. fundamental units C. metric prefixes D. international standards

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2. Which of the following metric prefixes could replace 10–9?

A. Nano B. Mega

C. Kilo D. Micro

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3. Scientific notation is a method

A. of expressing a very large number B. of expressing a very small number

C. used to make calculations with large and small numbers D. All of the above

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4. If you drop a 5 when rounding a number, you are using the A. round-to-even rule

B. significant digit rule C. round-off rule D. retained digit rule

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5. 7200 mV is the same as A. 7.2 V

B. 7.2 V C. 7,200,000 V D. 0.0072 V

6. A measure of the repeatability of a measurement of some quantity is

A. error B. precision

C. accuracy D. significant

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7. Another name for "fundamental units" is A. base units

B. atoms

C. the metric system D. letter symbols

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8. Adding 27.5 × 103 to 8.9 × 104 equals

A. 36.4 × 107 B. 116.5 × 104 C. 28.39 × 103 D. 1.165 × 105

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9. When using the terms "accuracy" and "precision" for measurements A. "precision" implies less measurement error than "accuracy"

B. "accuracy" implies less measurement error than "precision"

C. "precision" measures the repeatability of a measurement D. both terms mean the same thing

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10. The difference between scientific and engineering notation is A. powers of ten representation

B. single vs. multiple digits before decimal point C. groupings of multiples of three digits

D. All of the above

11. The number 14.8 can also be expressed as A. 1.48 × 10–1

B. 1.48 × 100 C. 1.48 × 101 D. 1.48 × 102

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12. The digits in a measured number that are known to be correct are called A. accuracy digits

B. significant digits C. error digits D. precision digits

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13. Which of the following is expressed in engineering notation?

A. 470 × 105 B. 82 × 10–2 C. 9.1 × 10–6 D. 14.7 × 108

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14. The unit for frequency is the

A. hertz B. ampere

C. watt D. second

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15. Add 21 mA and 8000 A and express the result in milliamperes.

A. 21.8 mA B. 218 mA C. 29 mA

D. 290 mA

16. Dividing 24 ×

1011 by 3 × 104 equals

A. 8 × 104 B. 8 × 107 C. 8 × 1011 D. 8 × 1015

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17. Pico is what relation to micro?

A. one-tenth B. one-hundredth

C. one-thousandth D. one-millionth

XI - Ohm's Law

1. "Half-splitting" is

A. a means for nuclear fuel cells to produce electricity

B. a means of isolating a problem in a circuit

C. a means for reducing a high ac voltage to a low dc voltage

D. a means of limiting current in a circuit

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2. If doubling the voltage across a resistor doubles the current through the resistor then

A. the resistor value decreased B. the resistor value did not change C. the resistor value increased

D. it is impossible to determine the change in the resistor value

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3. If the voltage across a fixed value of resistance is increased five times, what does the current do?

A. It increases by a factor of five.

B. It decreases by a factor of five.

C. It stays the same.

D. Not enough information

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4. If the resistance in a circuit with constant voltage increases, the current will

A. increase B. decrease C. stay the same

D. Not enough information

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5.

What is the power in the given circuit?

A. 3.6 W B. 35 W C. 175 W D. 245 W

6. What is the kilowatt-hour consumption of a 40 W lamp if it remains on for 1750 h?

A. 43.75 B. 70

C. 43,750 D. 70,000

(1,750 x 40)/1000 = 70 kilowatt-hour.

7. A damaged resistor A. may appear burned

B. may have an increased resistance value

C. may be checked with an ohmmeter

D. All of the above

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8. Power supplies differ from batteries in that

A. power supply output voltages are ac and not dc

B. power supply voltages are not stable

C. power supplies are low-current devices

D. None of the above

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9.

What is the resistor value in the given circuit?

A. 200 B. 1 k C. 2 k D. 4 k

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10. If voltage across a resistance doubles A. the current is halved

B. the resistance doubles C. the current is unchanged D. none of the above

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What is the power in the given circuit?

A. 32 W

B. 80 W C. 500 W D. 16 kW

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12. Ohm's law describes the mathematical relationship between

A. ohms, kilohms, and megohms B. resistor size and resistor value C. resistance, voltage, and current D. none of the above

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13. Energy is defined as the ability to A. produce heat

B. produce light C. produce sound D. All of the above

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14. What electromotive force would cause 20 A of current to flow through a 500 resistor?

A. 0.04 V B. 2.5 V C. 25.0 V D. 10,000 V

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15. The rate at which work is performed is called

A. current B. energy

C. power D. voltage

16. A battery's capacity to deliver power is measured in

A. kWh B. Ah

C. Wh D. Vh

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17. Power supplies are regulated to prevent the output voltage from changing due to changes in the

A. line voltage B. supply load C. frequency

D. both line voltage and supply load

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18.

What is the power in the given circuit?

A. 3.92 kW B. 280 W C. 28.6 W D. 9.8 W

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19. If current through a resistance is halved A. the resistance is halved

B. the voltage is halved C. the voltage doubles D. none of the above

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20. Ohm's law is a relationship between A. voltage, current, and time B. power, current, and resistance C. resistance, time, and current D. voltage, current, and resistance