NYC DCAS ELECTRICIAN PRACTICE
EXAM 3 Questions and Answers with
Rationales Latest Versions
1.Question
A 120-volt circuit supplies a 24-ohm resistive load. What current flows through the
load?
A. 2 A
B. 5 A
C. 10 A
D. 24 A
Correct Answer: B. 5 A
Rationale:
Using Ohm's law:
[
I=\frac{V}{R}
]
[
I=\frac{120}{24}=5A
]
Therefore, the current is 5 amperes.
Question 2
A circuit carries 10 A through a resistance of 12 Ω. What is the voltage?
A. 60 V
B. 100 V
C. 120 V
D. 240 V
,Correct Answer: C. 120 V
Rationale:
[
V=I\times R
]
[
V=10\times12=120V
]
The circuit voltage is 120 volts.
Question 3
What happens to the total resistance when resistors are connected in series?
A. It is the sum of the individual resistances
B. It is always less than the smallest resistor
C. It becomes zero
D. It is always equal to the largest resistor
Correct Answer: A. It is the sum of the individual resistances
Rationale:
For series resistors:
[
R_T=R_1+R_2+R_3+\ldots
]
Thus, each additional series resistor increases total resistance.
Question 4
Four 12-Ω resistors are connected in parallel. What is the equivalent resistance?
,A. 3 Ω
B. 12 Ω
C. 24 Ω
D. 48 Ω
Correct Answer: A. 3 Ω
Rationale:
For four identical resistors in parallel:
[
R_T=\frac{12}{4}=3\Omega
]
Question 5
Which law states that current is equal to voltage divided by resistance?
A. Faraday's law
B. Ohm's law
C. Kirchhoff's current law
D. Lenz's law
Correct Answer: B. Ohm's law
Rationale:
Ohm's law is:
[
I=\frac{V}{R}
]
It describes the relationship between voltage, current, and resistance.
Question 6
A 240-V heater draws 10 A. What is its approximate power consumption?
, A. 240 W
B. 1,200 W
C. 2,400 W
D. 4,800 W
Correct Answer: C. 2,400 W
Rationale:
[
P=V\times I
]
[
P=240\times10=2,400W
]
Question 7
Which instrument is most appropriate for measuring current without disconnecting
a conductor from the circuit?
A. Clamp meter
B. Ohmmeter
C. Megohmmeter only
D. Thermometer
Correct Answer: A. Clamp meter
Rationale:
A clamp meter measures current by sensing the magnetic field around a
conductor, allowing current measurement without opening the circuit in many
applications.
Question 8
When using a conventional ohmmeter, the circuit should generally be:
EXAM 3 Questions and Answers with
Rationales Latest Versions
1.Question
A 120-volt circuit supplies a 24-ohm resistive load. What current flows through the
load?
A. 2 A
B. 5 A
C. 10 A
D. 24 A
Correct Answer: B. 5 A
Rationale:
Using Ohm's law:
[
I=\frac{V}{R}
]
[
I=\frac{120}{24}=5A
]
Therefore, the current is 5 amperes.
Question 2
A circuit carries 10 A through a resistance of 12 Ω. What is the voltage?
A. 60 V
B. 100 V
C. 120 V
D. 240 V
,Correct Answer: C. 120 V
Rationale:
[
V=I\times R
]
[
V=10\times12=120V
]
The circuit voltage is 120 volts.
Question 3
What happens to the total resistance when resistors are connected in series?
A. It is the sum of the individual resistances
B. It is always less than the smallest resistor
C. It becomes zero
D. It is always equal to the largest resistor
Correct Answer: A. It is the sum of the individual resistances
Rationale:
For series resistors:
[
R_T=R_1+R_2+R_3+\ldots
]
Thus, each additional series resistor increases total resistance.
Question 4
Four 12-Ω resistors are connected in parallel. What is the equivalent resistance?
,A. 3 Ω
B. 12 Ω
C. 24 Ω
D. 48 Ω
Correct Answer: A. 3 Ω
Rationale:
For four identical resistors in parallel:
[
R_T=\frac{12}{4}=3\Omega
]
Question 5
Which law states that current is equal to voltage divided by resistance?
A. Faraday's law
B. Ohm's law
C. Kirchhoff's current law
D. Lenz's law
Correct Answer: B. Ohm's law
Rationale:
Ohm's law is:
[
I=\frac{V}{R}
]
It describes the relationship between voltage, current, and resistance.
Question 6
A 240-V heater draws 10 A. What is its approximate power consumption?
, A. 240 W
B. 1,200 W
C. 2,400 W
D. 4,800 W
Correct Answer: C. 2,400 W
Rationale:
[
P=V\times I
]
[
P=240\times10=2,400W
]
Question 7
Which instrument is most appropriate for measuring current without disconnecting
a conductor from the circuit?
A. Clamp meter
B. Ohmmeter
C. Megohmmeter only
D. Thermometer
Correct Answer: A. Clamp meter
Rationale:
A clamp meter measures current by sensing the magnetic field around a
conductor, allowing current measurement without opening the circuit in many
applications.
Question 8
When using a conventional ohmmeter, the circuit should generally be:
