Deck 3: Ohms Law

Question 1

When taking current measurements, it is extremely important not to accidentally place the meter
across the voltage source.

Answer 1

True

Question 2

If a resistor carries 5 mA, itʹs safe to use a 1 W resistor.

Answer 2

False

Question 3

Power rating for a resistor is mainly based on the physical size.

Answer 3

True

Question 4

According to Ohmʹs Law, if voltage were to decrease while resistance remained the same, current would

A)decrease
B)no way to determine
C)remain the same
D)increase

Question 5

If a circuitʹs resistance increases, its current decreases.

Question 6

Voltage and current are ________.

A)quantities that add
B)unrelated
C)inversely proportional
D)directly proportional

Question 7

If a resistor carries 45 mA, it is dissipating 5.0625 W.

Question 8

If the current is constant, voltage and resistance are directly proportional.

Question 9

An electronic power supply with a rated current capacity of 500 mA can adequately illuminate a 10
V @ 5 W lamp.

Question 10

If a circuitʹs resistance decreases, its current also decreases.

Question 11

If a circuitʹs supply voltage is 20 V and its resistance is its current is 6.06 mA.

Question 12

If a resistor has 32 mA flowing through it, it dissipates 1.024 W.

Question 13

If a resistor carries 10 mA, it is safe to use a 10 W resistor.

Question 14

If the voltage across a circuit increases, ________.

A)the resistance increases
B)the resistance decreases
C)the current decreases
D)the current increases

Question 15

If the voltage applied to a circuit doubles, then power dissipation doubles.

Question 16

If a resistor carries 12 mA, the resistor drops 1 V.

Question 17

If a circuitʹs supply voltage is 15 V and its resistance is , its current is 3.19 mA.

Question 18

According to Ohmʹs Law, if voltage were to increase while resistance remained the same, current would

A)remain the same
B)increase
C)no way to determine
D)decrease

Question 19

If V = 25 V and in Figure 3-1, the current equals ________.

A)0.5 mA
B)5 mA
C)2 mA
D)50 mA

Question 20

According to Ohmʹs Law, if resistance were to decrease while voltage remained the same, current would

A)increase
B)no way to determine
C)remain the same
D)decrease

Question 21

If V = 100 V and I = 1 mA in Figure 3-1, the power dissipated by the resistor equals ________.

A)1 W
B)10 W
C)100 mW
D)10 mW

Question 22

If I = 32 mA and in Figure 3-1, the voltage equals ________.

A)19 V
B)22 V
C)15 V
D)12 V

Question 23

If the voltage is suddenly switched off in Figure 3-1, ________.

A)the current will suddenly drop to 0 A
B)the current will first increase and then decrease to 0 A
C)the current will gradually decrease to 0 A
D)there is no way to predict the current

Question 24

If V = 85 V and I = 15 mA in Figure 3-1, the resistance equals ________.

A)
B)
C)
D)

Question 25

If and in Figure 3-1, the current equals ________.

A)2 mA
B)50 mA
C)0.5 mA
D)5 mA

Question 26

If the voltage were suddenly switched on in Figure 3-1, ________.

A)the current would be zero
B)the current would gradually decrease and then increase
C)the current would flow
D)the current would gradually decrease

Question 27

If I = 45 mA and in Figure 3-1, the voltage equals ________.

A)1.125 V
B)1800 V
C)1.8 V
D)18 V

Question 28

If V=12V and a resistor were to open in Figure 3-1, the current is ________.

A)0 A
B)10 mA
C)1 mA
D)extremely high

Question 29

If I = 64 mA and in Figure 3-1, the voltage equals ________.

A)73.4 V
B)3.01 V
C)7.34 V
D)30.1 V

Question 30

If V = 12 V and a resistor shorts in Figure 3-1, the current is ________.

A)0 A
B)10 mA
C)1 mA
D)extremely high

Question 31

If the resistor opens in Figure 3-1, the ________.

A)resistance decreases
B)circuit current drops to 0 A
C)power dissipation increases
D)source voltage decreases to 0 V

Question 32

If I = 64 mA and in Figure 3-1, the voltage equals ________.

A)7.34 V
B)3.01 V
C)30.1 V
D)73.4 V

Question 33

If V = 50 V and I = 37 mA in Figure 3-1, ________ is dissipated by the resistor.

A)1.85 W
B)1.35 W
C)135 m W
D)0.185 m W

Question 34

If a 1/2 W resistor is used in the circuit in Figure 3-1, the current value ________.

A)depends upon the circuitʹs voltage and resistance
B)depends upon the voltage applied
C)is over 12 mA
D)is less than 12 mA

Question 35

If V = 60 V and in Figure 3-1, the current equals ________.

A)0.128 mA
B)128 mA
C)1.28 mA
D)12.8 mA

Question 36

If V = 72 V and I = 12 mA in Figure 3-1, the resistance equals ________.

A)
B)
C)
D)

Question 37

If voltage is 12 V and the resistance is color-coded brown-black-orange in Figure 3-1, what are the minimum and maximum possible currents?

A)
B)
C)
D)

Question 38

If the voltage is 15 V and resistance is color coded red-red-brown-silver in Figure 3-1, what are the maximum and minimum possible current?

A)
B)
C)
D)none of these

Question 39

If the resistor opens in Figure 3-1, the following circuit conditions would exist.

A)resistor would read infinite resistance
B)no power dissipation
C)no current flow
D)all of the above

Question 40

If a resistor dissipates 0.5 W in Figure 3-1, then the supply voltage equals ________.

A)7.07 mV
B)5000 V
C)70.7 V
D)50 V

Question 41

The power rating of a resistor that must dissipate up to 1.1 W should be ________.

A)5 W
B)0.25 W
C)2 W
D)1 W

Question 42

A resistor has burned open, so you look in your parts box to find a replacement. Which one of the following resistors could you use to repair the circuit?

A)
B)
C)
D)

Question 43

If a resistor that is color coded yellow-violet-red is placed across a 25 V source voltage, what value resistor and wattage rating could be used?

A)
B)
C)
D)

Question 44

If a resistance of is connected across a 1 kV source, current equals about ________.

A)0.455 mA
B)2.2 mA
C)0.455 A
D)

Question 45

If a resistor is rated at 1/2 W, it ________.

A)can only dissipate more than 1/2 W of power
B)always dissipates 1/2 W
C)always provides 1/2 W of power
D)can safely dissipate 1/2 W of power

Question 46

What is the resistance of a 100 W bulb when it is operating in a circuit with a supply of 120 V?

A)
B)
C)
D)

Question 47

If a resistor that is color-coded red-red-brown-silver is connected to a 15 V source, what is the maximum current that can flow?

A)75.8 mA
B)71.9 mA
C)62 mA
D)68.2 mA

Question 48

If a resistor dissipates 2 W, its voltage drop equals ________.

A)660 V
B)2.57 V
C)25.7 V
D)6.6 V

Question 49

If a resistor that is color-coded yellow-violet-orange-gold is placed across a 15 V source, the resistance and wattage rating could be ________.

A)
B)
C)
D)

Question 50

What is the resistance of a 150 W bulb when it is operating in a circuit with a supply of 125 V?

A)
B)
C)
D)

Question 51

Which is the correct formula for Ohmʹs Law?

A)I = V ÷ R
B)P = V × I
C)V = I ÷ R
D)R = V × I

Question 52

Using Wattʹs law and substituting power can be calculated as ________.

A)
B)
C)
D)all of these

Question 53

Resistance and current are ________.

A)similar to voltage
B)inversely proportional
C)not related
D)directly proportional

Question 54

If I = 27 mA and in Figure 3-1, the voltage equals ________.

A)7.8 V
B)5.74 V
C)174 mV
D)127 mV

Question 55

A current flowing through a resistor produces a ________ voltage drop.

A)18.8 V
B)1.18 V
C)53.2 V
D)1.18 mV

Question 56

If a resistor that is color-coded yellow-violet-brown-gold is connected to a 12 V source, then what is the current flow?

A)255 mA
B)26.9 mA
C)25.5 mA
D)24.3 mA

Question 57

Which is the correct formula for finding power?

A)
B)P = V × I
C)
D)all of these

Question 58

The symbol for a certain amount of energy used over time is ________.

A)W
B)P
C)V
D)I

Question 59

Power as it is used in electric circuits can be best defined as:

A)the rate voltage is applied over time.
B)the rate current flows over time.
C)the rate energy is used over time.
D)the rate motion is exerted over time.

Question 60

Which of the following terms is not a resistor rating?

A)resistor value in ohms
B)power rating
C)resistor tolerance
D)current

Question 61

If the current flow for a given circuit has doubled, then the ________ has been halved.

A)voltage
B)power
C)current
D)resistance

Question 62

The voltage of a power supply drops to 0 V when connected to a lamp circuit. What is a possible problem?

A)the lamp is open
B)the lamp is shorted
C)the lamp requires more current than the power supply can deliver
D)both B and C

Question 63

Which is the most unlikely resistor failure?

A)shorting
B)resistance change
C)opening
D)All are common failures.

Question 64

In the operation of electrical circuits, which, in most cases, is an unwanted by-product?

A)heat
B)mechanical motion
C)light
D)both B and C

Question 65

The ampere-hour rating of a battery is defined as the:

A)number of hours per amperes supplied.
B)number of amperes supplied in 1 hour.
C)number of amperes supplied over the number of hours at a given current.
D)all of these.

Question 66

Typically, which is the first type of measurement taken in a known defective circuit?

A)current
B)resistance
C)power
D)voltage

Question 67

A kilowatt-hour is best defined as:

A)a kilo multiplied by 1 watt-hour.
B)1,000 watts multiplied by 1 hour.
C)a kilo divided by 1 watt-hour.
D)1,000 watts divided by 1 hour.