ELECTRICAL THEORY: TRANSFORMERS, POWER, AND
POWER FACTOR (PART 3 UPDATED ACTUAL QUESTIONS
AND CORRECT ANSWERS
Question:
1. What is the primary function of a transformer?
Answer:
To transfer alternating current and voltage from one circuit to another using induction.
Question:
2. What are the main components of a simple transformer?
Answer:
A set of wire coils or windings around an iron core.
Question:
3. How does a transformer induce voltage?
Answer:
Through the expanding and collapsing magnetic field in the primary winding.
Question:
4. What is the relationship between primary and secondary voltages in a transformer?
Answer:
The ratio of the output voltage to the input voltage is approximately equal to the ratio of the number of
turns in the secondary coil to the primary coil.
Question:
5. What is the efficiency of a typical transformer?
Answer:
About 95% efficient.
Question:
6. Why is alternating current (AC) preferred in residential wiring?
Answer:
It provides greater flexibility in voltage selection and simplicity of equipment design.
, Question:
7. What is impedance in an AC circuit?
Answer:
A measure of resistance to current flow due to the combined effects of resistance, inductance, and
capacitance.
Question:
8. What does real power (P) represent?
Answer:
The portion of power that results in a net transfer of energy to do useful work, measured in Watts (W).
Question:
9. What is reactive power (Q)?
Answer:
Power required to generate magnetic fields for inductive devices, expressed in volt-amperes reactive
(VAR).
Question:
10. Define apparent power (S).
Answer:
The total power available to use, computed as the product of measured voltage and current, expressed in
volt-amperes (VA).
Question:
11. What is the power factor (pf)?
Answer:
The ratio of real power to apparent power in a circuit.
Question:
12. What happens to the power factor in purely resistive circuits?
Answer:
Voltage and current peaks are synchronized, resulting in a power factor of 1.0.
Question:
13. What causes a low power factor?
Answer:
A greater amount of inductive load than capacitive load in the circuit.
POWER FACTOR (PART 3 UPDATED ACTUAL QUESTIONS
AND CORRECT ANSWERS
Question:
1. What is the primary function of a transformer?
Answer:
To transfer alternating current and voltage from one circuit to another using induction.
Question:
2. What are the main components of a simple transformer?
Answer:
A set of wire coils or windings around an iron core.
Question:
3. How does a transformer induce voltage?
Answer:
Through the expanding and collapsing magnetic field in the primary winding.
Question:
4. What is the relationship between primary and secondary voltages in a transformer?
Answer:
The ratio of the output voltage to the input voltage is approximately equal to the ratio of the number of
turns in the secondary coil to the primary coil.
Question:
5. What is the efficiency of a typical transformer?
Answer:
About 95% efficient.
Question:
6. Why is alternating current (AC) preferred in residential wiring?
Answer:
It provides greater flexibility in voltage selection and simplicity of equipment design.
, Question:
7. What is impedance in an AC circuit?
Answer:
A measure of resistance to current flow due to the combined effects of resistance, inductance, and
capacitance.
Question:
8. What does real power (P) represent?
Answer:
The portion of power that results in a net transfer of energy to do useful work, measured in Watts (W).
Question:
9. What is reactive power (Q)?
Answer:
Power required to generate magnetic fields for inductive devices, expressed in volt-amperes reactive
(VAR).
Question:
10. Define apparent power (S).
Answer:
The total power available to use, computed as the product of measured voltage and current, expressed in
volt-amperes (VA).
Question:
11. What is the power factor (pf)?
Answer:
The ratio of real power to apparent power in a circuit.
Question:
12. What happens to the power factor in purely resistive circuits?
Answer:
Voltage and current peaks are synchronized, resulting in a power factor of 1.0.
Question:
13. What causes a low power factor?
Answer:
A greater amount of inductive load than capacitive load in the circuit.
