ohm's lawwcvtc.wyom.k12.wv.us/electricalntid.pdf · ohms law worksheet multiple choice use the...

OHM'S LAW

Name: Date:

Ohms Law Worksheet

Multiple Choice Use the Ohm's Law Formula Sheet to identify the choice that best completes the statement or answers the question.

I. A circuit is rated at 8.75 kW. This is the same as a. 875 watts c. 87,500 watts b. 8750 watts d. 62.5 watts

2. How much current will exit in a lamp that has a resistance of 100 ohms and is connected across a 240-volt circuit? a. 2.4 amps c. 5.1 amps b. 4.9 amps d. 4.4 amps

3. Two resistors are connected in parallel. One has a value of 100 ohms the other has a value of 65 ohms. What is the total ohms of the two resistors?

R1 x R2 R1 + R2

a. 39.39 Ohms c. 50.25 Ohms

b. 48.25 Ohms

d. 155.55 Ohms

4. A circuit rated at 4.5kW. What is the current if the applied voltage is 120 VAC? a. 21.5 amps c. 37.5 amps b. 30.5 amps d. 10.8 amps

5. How much current will exist in a lamp that has a resistance of 400 ohms and is connected across a 80-volt circuit? a. 4 amps c. 5.1 amps b. .45 amps d. .tamps

6. What current will exist in a 6,500 watt electric iron when a voltage of 240 volts is maintained? a. 1.458 amps c. 145.8 amps b. 27.08 amps d. .1458amps

7. What is the 40% load of a 20-amp circuit? a. 12 amps b. 10 amps

c. 8 amps d. 9 amps

1

5 2

5 0 0 0 O 0 0 0 H H H H

M M 1;1 S S S

T Ts T T

a. 100.543 ohms c. 24.234 ohms b. 64.649 ohms

d. 183.893 ohms

9. What is the total resistance of the circuit below:

± I 2 6 7 7 5 0 O 0

M S S

T

5 3 0 0 H M

a. 48.82

c. 18.87 b. 63.88

d. 58.82

I 1 0 0 0 H M S

T

Name: ID: A

8. Using the formula below, what is the total resistance in the circuit below?

I = TOTAL RESISTANCE I + I + 1 + 1

RI R2 R3 R4

10. What is the total resistance of three 210 ohm resistors in parallel? a. 22.3 ohms c. 24.5 ohms b. 70.02 ohms d. 2.88 ohms

11. What is the total wattage of an electric heater that draws 10 amps and has 6 ohms of resistance? a. 15.37 watts c. 16.66 watts b. 6 watts d. 60.25 watts

12. Thirty-one degrees Celsius is equal to degrees Fahrenheit.

F=(Cx 1.8)+32

a. 103.5 b. 100.8

c. 87.8 d. 99.6

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Name: ID: A

13. Eight light bulbs are installed on one circuit, two at 40 watts, one at 25 watts, two at 75 watts and two at 7.5 watts. If the total amperage on the circuit is 4 amps, what is the applied voltage? a. 62 volts c. 67.5 volts b. 62.75 volts d. 675 volts

The "I" in Ohm's Law is used to represent a. Current c. Resistance b. Voltage d. Power

14.

15. How much current will exist in a 275 watt lamp that has a resistance of 11 ohms?

16.

a. 5 amps c. 6 amps b. 4 amps d. 9 amps

What is the decimal equivalent of 13/16 ? a. .875 c. .9375 b. .8125 d. .750

17. Forty four degrees Celsius is equal to F=(C x 1.8) + 32

a. 108.5 b. 112.2

degrees Fahrenheit.

c. 186.5 d. 66.5

18. Seven light bulbs are installed on one circuit, two at 40 watts, one at 25 watts, two at 75 watts and two at 7.5 watts. If the total amperage on the circuit is 4 amps, what is the applied voltage? a. 62 volts c. 67.5 volts b. 62.75 volts d. 675 volts

19. What is the total resistance of the circuit below:

± 1 7 5

H M S

5 7 0 0 H M S

0

O H M

4 3 0 0 H M S

3 3 0 0 H M

T

1 0 0 0 H M S

T a. 48.82 c. 44.25

b. 63.88

d. 46.24

20. What is the 80% load of a 30•amp circuit?

a. 20 amperes b. 24 amperes

c. 16 amperes d. 14 amperes

3

Name: ID: A

21. What current will exist in a 3,500 watt electric iron when a voltage of 240 volts is maintained? a. 1.458 amps c. 145.8 amps b. 14.58 amps d. .1458amps

22. Sixty-four degrees Fahrenheit is equal to degrees Celsius. C.= (F - 32) / 1.8

a. 68.5

c. 86.5 b. 75.2

d. 17.77

23. Sixty one degrees Fahrenheit is equal to degrees Celsius. C=(F - 32)/1.8 a. 68.53 c. 48.55 b. 75.24 d. 16.11

24. What is the total resistance of a parallel circuit containing the following resistors?

475 Ohms, 330 Ohms, 500 Ohms, 120 Ohms

a. 100.543 ohms c. 24.234 ohms b. 64.649 ohms d. 183.893 ohms

25. Two resistors are connected in parallel. One has a value of 88 ohms the other has a value of 110 ohms. What is the total ohms of the two resistors? a. 48.88 Ohms c. 50.25 Ohms b. 148.25 Ohms d. 155.55 Ohms

26. What is the total resistance of a circuit connected to a 240 volt power source drawing 25 amps? a. 16 Ohms c. 18.2 Ohms b. 9.6 Ohms d. 7.4 Ohms

27. How much current will exist in a lamp that has a resistance of 120 ohms and is connected across a 60-volt circuit? a. 4 amps c. 9.8 amps b. .25 amps d. .5 amps

28. Twenty-four degrees Celsius is equal to a. 70.5 b. 75.2

degrees Fahrenheit. c. 86.5 d. 66.5

29. Seventy-one degrees Celsius is equal to degrees Fahrenheit.

a. 103.5

c. 159.8 b. 100.8

d. 99.6

4

30. The following resistors are connected in series. What is the total resistance of the circuit?

125 Ohms, 49 Ohms, 18 Ohms, 43 Ohms, 21 Ohms

a. 468 Ohms c. 256 Ohms b. 198 Ohms

d. 1256 Ohms

Vd = Cm =

VOLTAGE DROP

2 xKxLx1

Cm

VOLTAGE DROP

2 xKxLx1

Vd

Vd Voltage Drop I Current L Length one way K Resistance 12.9 Copper, 21.2 Aluminum

Cm Circular Mils

Vd Voltage Drop I Current L Length one way K Resistance 12.9 Copper, 21.2 Aluminum

Cm Circular Mils

Name: Date:

Voltage Drop Review

True/False Indicate whether the statement is true or false.

1. A 240 volt branch circuit is allowed a 3 percent voltage drop. The minimum voltage allowed at the last receptacle on the branch circuit is 232.8 volts.

Multiple Choice Identib) the choice that best completes the statement or answers the question.

2. What is the total voltage drop for a 2500 foot long circuit to a 277 volt 15 ampere load, and back on a neutral, using a 8 AWG stranded copper conductor. Use the formula below.

a. 25.00 Volts c. 52.00 Volts b. 40.25 Volts

d. 58.60 Volts



d. 6.33 Volts

4. What is the total voltage drop for a 1875 foot, 460 volt, 8 ampere circuit using 10 AWG copper conductor.


d. 58.60 Volts



d. 9.33 Volts



d. 39.33 Volts

7. What is the total voltage drop for a 875 foot, 480 volt, 6 ampere circuit using 12 AWG aluminum conductor.


d. 58.60 Volts

8. What is the total voltage drop for a 500 foot, 208 volt, 6 ampere circuit using 12 AWG aluminum conductor.

a. 25.00 Volts c. 52.00 Volts b. 19.47

d. 58.60 Volts

1

Name: ID: A


a. 4.35 Volts b. 2.45 Volts

c. 1.85 Volts d. 9.33 Volts


a. 10.25 Volts b. 12.05 Volts

c. 8.85 Volts d. 6.33 Volts

Short Answer

11. What is the minimum circular mils for a copper conductor to maintain a 3% voltage drop in a branch circuit that is rated at 15 amps, 120 volts and is 60 feet long (one way)?

12. What is the minimum circular mils for a aluminum conductor needed to maintain a 3% voltage drop in a branch circuit that is rated at 15 amps, 240 volts and is 98 feet long (one way)?

13. What is the minimum circular mils for a aluminum conductor needed to maintain a 2% voltage drop in a branch circuit that is rated at 20 amps, 480 volts and is 120 feet long (one way)?

14. What is the minimum circular mils for a copper conductor needed to maintain a 2 % voltage drop in a branch circuit that is rated at 30 amps, 120 volts and is 500 feet long (one way)?

15. What is the minimum circular mils for a copper conductor needed to maintain a 1 % voltage drop in a branch circuit that is rated at 50 amps, 240 volts and is 165 feet long (one way)?

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Name: Date:

Career Assignment

Essay

I. Choose a career in the electrical industry (Master Electrician, Electrical Engineer, etc.) that you are interested in pursuing. Answer the questions below about your choice.

1. What position in the electrical industry are you most interested in pursuing?

2. What type of education or training is required for the position?

3. What is the average annual salary for the position?

4. List five job duties of this position?

5. Write a one page paper describing what interest you about this position. Attach the completed one page paper to this worksheet.

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Name: Date:

Switch Replacment

Essay

1. Describe in detail, the steps for replacing a single pole switch. Steps one and two are outlined as examples.

Step One: Identify and turn off the power to the lighting circuit.

Step Two: Lock out the circuit so it will not be energized while you are replacing the switch.

Step Three:

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Name: . Date:

National Electric Code

Essay

1. Write a one page essay on the history of the National Electric Code. Describe why the National Electric code was written, when the first National Electric Code was published and how often it is revised

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