Deck 3: Ohms Law, Energy, and Power

Question 1

$$\text { Figure } 3 < 1$$

-If V=25 V and R=50 $\mathrm { k } \Omega$
in Figure 3-1 , the current equals________

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

Answer 1

0.5 mA

Question 2

If a 56 $\mathrm { k } \Omega$ resistor carries 10mA , it is safe to use a 10W resistor.

Answer 2

True

Question 3

According to Ohmʹs Law, if voltageW ere to increaseW hile resistance remained the same, current would

A)remain the same
B)increase
C)noW
Ay to determine
D)decrease

Answer 3

increase

Question 4

If a circuitʹs resistance increases, its current decreases.

Question 5

According to Ohmʹs Law, if resistanceW ere to decreaseW hile voltage remained the same, current would

A)increase
B)noW
Ay to determine
C)remain the same
D)decrease

Question 6

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

Question 7

If a circuit's supply voltage is 15 V and its resistance is 4700 , its current is 3.19 mA .

Question 8

According to Ohmʹs Law, if voltageW ere to decreaseW hile resistance remained the same, current would

A)decrease
B)noW
Ay to determine
C)remain the same
D)increase

Question 9

Voltage and current are ________.

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

Question 10

If a circuit's supply voltage is 20 V and its resistance is 3300 , its current is 6.06 mA .

Question 11

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

Question 12

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

Question 13

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

Question 14

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

Question 15

If a 47 resistor carries 5 mA , it's safe to use a 1 W resistor.

Question 16

If the voltage across a circuit increases, ________.

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

Question 17

If a circuitʹs resistance decreases, its current also decreases.

Question 18

If a 1 resistor has 32 mA flowing through it, it dissipates 1.024 W .

Question 19

If a 2.5 $\mathrm { k } \Omega$ resistor carries 45 mA , it is dissipating 5.0625 W.

Question 20

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

Question 21

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

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

Question 22

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 23

$$\text { Figure } 3 < 1$$

-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 24

$$\text { Figure } 3 < 1$$

-If V=50 V and R=25 $\mathrm { k } \Omega$
in Figure 3-1 , the current equals_________

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

Question 25

$$\text { Figure } 3 < 1$$

-If V=60 V and R=47 $\mathrm { k } \Omega$ in Figure 3-1 , the current equals______

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

Question 26

$$\text { Figure } 3 < 1$$

-If I=64 mA and R=470 in Figure 3-1 , the voltage equals_________

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

Question 27

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

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

Question 28

$$\text { Figure } 3 < 1$$

-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 29

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

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

Question 30

If the voltageW ere 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 31

$$\text { Figure } 3 < 1$$

-If V=12 V and a 12 $\mathrm { k } \Omega$ resistor were to open in Figure 3-1 , the current is resistor were to open in Figure 3-1 , the current is_____

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

Question 32

$$\text { Figure } 3 < 1$$

-If I=27 mA and R=4.7 $\Omega$ in Figure 3-1 , the voltage equals______

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

Question 33

$$\text { Figure } 3 < 1$$

-If I=32 mA and R=469 m in Figure 3-1 , the voltage equals______

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

Question 34

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) I_MINIMUM =1 mA , I_MAXIMUM =1.6 mA
B) I_MINIMUM =1.2 mA , I_MAXIMUM =1.4 mA
C) I_MINIMUM =1 mA , I_MAXIMUM =1.5 mA
D) I_MINIMUM =0.8 mA , I_MAXIMUM =1.2 mA

Question 35

$$\text { Figure } 3 < 1$$

-If a 10 $\mathrm { k } \Omega$ 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 36

$$\text { Figure } 3 < 1$$

-If I=64 mA and R=47 in Figure 3-1 , the voltage equals_____

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

Question 37

$$\text { Figure } 3 < 1$$

-If I=45 mA and R=40 $\mathrm { k } \Omega$ in Figure 3-1, the voltage equals_________

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

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) I_MINIMUM =64.9 mA, I_MAXIMUM=71.8 mA
B) I_MINIMUM =56.8 mA , I_MAXIMUM =85.2 mA
C) I_MINIMUM =62.0 mA , I_MAXIMUM =75.8 mA
D) none of these

Question 39

$$\text { Figure } 3 < 1$$

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

A) 1.28 $\Omega$
B) 567 $\Omega$
C) 5.67 $k \Omega$
D) 52.3 $\Omega$

Question 40

$$\text { Figure } 3 < 1$$

-If V=12 V and a 12 $\mathrm { k } \Omega$ resistor shorts in Figure 3-1 , the current is________

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

Question 41

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

A) 2.14
B) 104
C) 9375
D) 75

Question 42

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 43

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

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

Question 44

A 250 μA current flowing through a 4.7 kΩ resistor produces a ________ voltage drop.

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

Question 45

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 46

Using Watt's law and substituting power can be calculated as_________

A) $\mathrm { P } = \mathrm { I } ^2 \mathrm { R }$
B) P=V I
C) $\mathrm { P } = \mathrm { V }^ 2 / \mathrm { R }$
D) all of these

Question 47

If a 330 $\Omega$ resistor dissipates 2 W , its voltage drop equals_______

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

Question 48

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

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

Question 49

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 50

Which is the correct formula for finding power?

A)
B)
C)
D) all of these

Question 51

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

A) 56 $\Omega$
B) 560 $\Omega$
C) 2.14 $\Omega$
D) 144 $\Omega$

Question 52

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

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

Question 53

A 220 $\Omega$ 1/2 W 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) 2200 $\Omega$ 1/2 W
B) 220 $\Omega$ 1/4W
C) 220 $\Omega$ 1 W
D) 220 $\Omega$ 1/8 W

Question 54

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 55

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

A)the rateVoltage 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 56

If a resistance of 2.2 is connected across a 1 kV source, current equals about_______

A) 0.455 mA
B) 2.2 mA
C) 0.455 A
D) 45.5 $\mu \mathrm { A }$

Question 57

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

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

Question 58

Resistance and current are ________.

A)similar toVoltage
B)inversely proportional
C)not related
D)directly proportional

Question 59

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.

Question 60

Which of the following terms is not a resistor rating?

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

Question 61

Which is the most unlikely resistor failure?

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

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

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 64

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

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