Industrial Electrician Master Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. A three-phase induction motor is rated 415 V and draws 10 A at full
load with a power factor of 0.8. What is the approximate input power?
A) 4.8 kW
B) 5.77 kW
C) 7.2 kW
D) 6.9 kW
The input power for a three-phase system is calculated using P = √3 × V × I
× power factor, giving approximately 1.732 × 415 × 10 × 0.8 ≈ 5.77 kW,
which reflects real power consumed.
2. Which device is primarily used to protect electrical circuits from
overcurrent conditions?
,A) Contactor
B) Circuit breaker
C) Transformer
D) Relay
A circuit breaker automatically interrupts current flow when excessive
current is detected, preventing damage to wiring and equipment due to
overload or short circuits.
3. What is the function of a star-delta starter in motor control?
A) Increase motor speed
B) Reduce starting current
C) Increase torque at startup
D) Reverse motor direction
A star-delta starter reduces starting current by initially connecting the
motor windings in star configuration before switching to delta for normal
operation.
4. The resistance of a conductor increases with:
A) Decreasing temperature
B) Increasing length
C) Increasing cross-sectional area
D) Decreasing resistivity
Resistance is directly proportional to length; a longer conductor provides
more opposition to electron flow, increasing resistance.
, 5. Which instrument is used to measure insulation resistance?
A) Clamp meter
B) Megohmmeter
C) Ammeter
D) Wattmeter
A megohmmeter applies high DC voltage to measure very high resistance
values in insulation systems to ensure safety and reliability.
6. What is the primary purpose of earthing in electrical installations?
A) Increase voltage stability
B) Reduce current flow
C) Provide a low-resistance path to ground
D) Increase resistance of circuit
Earthing ensures fault currents are safely diverted to the ground,
protecting humans and equipment from electric shock.
7. In a transformer, eddy current losses are reduced by using:
A) Solid core
B) Copper winding
C) Laminated core
D) Aluminum casing
Laminated cores increase resistance to circulating currents, thereby
reducing energy losses due to eddy currents.
8. The unit of electrical power is:
, A) Volt
B) Ampere
C) Watt
D) Ohm
Watt is the SI unit of power, representing the rate of energy conversion or
transfer in an electrical system.
9. Which component is used to store electrical energy in an electric field?
A) Resistor
B) Inductor
C) Capacitor
D) Transformer
A capacitor stores energy in the form of an electric field between its plates
when voltage is applied.
10. What happens when a fuse blows in a circuit?
A) Voltage increases
B) Current increases
C) Circuit is interrupted
D) Resistance decreases
A fuse melts due to excessive current, breaking the circuit and stopping
current flow to protect equipment.
11. The slip of an induction motor is defined as:
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. A three-phase induction motor is rated 415 V and draws 10 A at full
load with a power factor of 0.8. What is the approximate input power?
A) 4.8 kW
B) 5.77 kW
C) 7.2 kW
D) 6.9 kW
The input power for a three-phase system is calculated using P = √3 × V × I
× power factor, giving approximately 1.732 × 415 × 10 × 0.8 ≈ 5.77 kW,
which reflects real power consumed.
2. Which device is primarily used to protect electrical circuits from
overcurrent conditions?
,A) Contactor
B) Circuit breaker
C) Transformer
D) Relay
A circuit breaker automatically interrupts current flow when excessive
current is detected, preventing damage to wiring and equipment due to
overload or short circuits.
3. What is the function of a star-delta starter in motor control?
A) Increase motor speed
B) Reduce starting current
C) Increase torque at startup
D) Reverse motor direction
A star-delta starter reduces starting current by initially connecting the
motor windings in star configuration before switching to delta for normal
operation.
4. The resistance of a conductor increases with:
A) Decreasing temperature
B) Increasing length
C) Increasing cross-sectional area
D) Decreasing resistivity
Resistance is directly proportional to length; a longer conductor provides
more opposition to electron flow, increasing resistance.
, 5. Which instrument is used to measure insulation resistance?
A) Clamp meter
B) Megohmmeter
C) Ammeter
D) Wattmeter
A megohmmeter applies high DC voltage to measure very high resistance
values in insulation systems to ensure safety and reliability.
6. What is the primary purpose of earthing in electrical installations?
A) Increase voltage stability
B) Reduce current flow
C) Provide a low-resistance path to ground
D) Increase resistance of circuit
Earthing ensures fault currents are safely diverted to the ground,
protecting humans and equipment from electric shock.
7. In a transformer, eddy current losses are reduced by using:
A) Solid core
B) Copper winding
C) Laminated core
D) Aluminum casing
Laminated cores increase resistance to circulating currents, thereby
reducing energy losses due to eddy currents.
8. The unit of electrical power is:
, A) Volt
B) Ampere
C) Watt
D) Ohm
Watt is the SI unit of power, representing the rate of energy conversion or
transfer in an electrical system.
9. Which component is used to store electrical energy in an electric field?
A) Resistor
B) Inductor
C) Capacitor
D) Transformer
A capacitor stores energy in the form of an electric field between its plates
when voltage is applied.
10. What happens when a fuse blows in a circuit?
A) Voltage increases
B) Current increases
C) Circuit is interrupted
D) Resistance decreases
A fuse melts due to excessive current, breaking the circuit and stopping
current flow to protect equipment.
11. The slip of an induction motor is defined as:
