ETA CERTIFIED ELECTRONICS TECHNICIAN - ASSOCIATE (CETa) 2026/2027 –
300 QUESTION PRACTICE EXAM BANK
DOMAIN 1: DC CIRCUITS & ANALYSIS
A resistor has color bands: Yellow, Violet, Orange, Gold. What is its value?
A) 4.7kΩ ±5%
B) 47kΩ ±5%
C) 470Ω ±5%
D) 47Ω ±5%
Answer: B
1. Rationale: Yellow=4, Violet=7, Orange=×1000, Gold=±5%.
47×1000=47,000Ω=47kΩ.
If a 12V battery supplies 2A to a load, what is the power dissipated?
A) 6W
B) 24W
C) 14W
D) 10W
Answer: B
2. Rationale: P=VI. 12V × 2A = 24W.
In a series circuit with three equal resistors, total resistance is 300Ω. What is
the value of one resistor?
A) 100Ω
B) 300Ω
C) 900Ω
D) 30Ω
Answer: A
3. Rationale: Rt = R1 + R2 + R3. 300Ω / 3 = 100Ω.
Which equation correctly calculates total resistance for two parallel resistors
(R1 and R2)?
A) R1 + R2
B) 1/R1 + 1/R2
C) (R1 × R2) / (R1 + R2)
D) (R1 + R2) / (R1 × R2)
Answer: C
, 4. Rationale: The product-over-sum rule is the standard shortcut for two
parallel resistors.
A Battery Management System (BMS) primarily prevents what condition in
lithium-ion packs?
A) Overvoltage and undervoltage
B) Short circuits in the load
C) RF interference
D) AC ripple
Answer: A
5. Rationale: 2026 BMS updates emphasize cell balancing and protection
against overcharge/over-discharge to prevent thermal runaway.
According to Kirchhoff's Voltage Law (KVL), the sum of voltages around a closed
loop is:
A) Equal to the current
B) Zero
C) Equal to the largest resistance
D) Infinite
Answer: B
6. Rationale: KVL states the algebraic sum of all voltages in a closed loop
equals zero.
What is the current through a 4Ω resistor if the voltage drop across it is 20V?
A) 5A
B) 80A
C) 16A
D) 0.2A
Answer: A
7. Rationale: I = V/R = 20/4 = 5A.
How should an ammeter be connected in a circuit?
A) In parallel
B) In series
C) Across the load
D) With the power off only
Answer: B
, 8. Rationale: Ammeters measure current and must be in series to ensure all
current flows through the meter.
A circuit has a 10V source and two 5Ω resistors in series. What is the voltage
drop across one resistor?
A) 10V
B) 2.5V
C) 5V
D) 7.5V
Answer: C
9. Rationale: Series circuit current is 10V/10Ω = 1A. Voltage drop = 1A × 5Ω =
5V. It acts as a voltage divider.
Energy efficiency in a DC-DC converter is calculated as:
A) Pout / Pin
B) Pin / Pout
C) Pin - Pout
D) Pin + Pout
Answer: A
10.Rationale: Efficiency (η) is the ratio of useful output power to total input
power.
What is the maximum power transfer theorem condition?
A) Load resistance equals source resistance
B) Load resistance is zero
C) Load resistance is infinite
D) Source resistance is zero
Answer: A
11. Rationale: Maximum power is transferred to the load when RL = RS.
Which meter setting measures continuity?
A) DC Volts
B) AC Amps
C) Ohms / Diode test
D) Frequency
Answer: C
12.Rationale: Ohms setting checks for a low-resistance path (continuity).
Three 12Ω resistors are connected in parallel. Total resistance is:
, A) 36Ω
B) 4Ω
C) 6Ω
D) 12Ω
Answer: B
13.Rationale: 1/Rt = 1/12 + 1/12 + 1/12 = 3/12. Rt = 12/3 = 4Ω.
A potentiometer has three terminals. It is primarily used as a:
A) Fixed resistor
B) Voltage divider
C) Current limiter
D) Capacitor
Answer: B
14.Rationale: The wiper sliding across the resistive element creates an
adjustable voltage divider.
If power is 50W and voltage is 120V, what is the resistance?
A) 2.4Ω
B) 288Ω
C) 6000Ω
D) 0.4Ω
Answer: B
15.Rationale: P = V²/R -> R = V²/P = (120²)/50 = 14400/50 = 288Ω.
An open circuit in a series network will cause:
A) Total current to drop slightly
B) Total current to become zero
C) Total voltage to drop to zero
D) Resistance to decrease
Answer: B
16.Rationale: An open breaks the current path; I = 0.
Kirchhoff's Current Law (KCL) states that current entering a node equals:
A) Voltage leaving the node
B) Current leaving the node
C) Resistance at the node
D) Power at the node
Answer: B
300 QUESTION PRACTICE EXAM BANK
DOMAIN 1: DC CIRCUITS & ANALYSIS
A resistor has color bands: Yellow, Violet, Orange, Gold. What is its value?
A) 4.7kΩ ±5%
B) 47kΩ ±5%
C) 470Ω ±5%
D) 47Ω ±5%
Answer: B
1. Rationale: Yellow=4, Violet=7, Orange=×1000, Gold=±5%.
47×1000=47,000Ω=47kΩ.
If a 12V battery supplies 2A to a load, what is the power dissipated?
A) 6W
B) 24W
C) 14W
D) 10W
Answer: B
2. Rationale: P=VI. 12V × 2A = 24W.
In a series circuit with three equal resistors, total resistance is 300Ω. What is
the value of one resistor?
A) 100Ω
B) 300Ω
C) 900Ω
D) 30Ω
Answer: A
3. Rationale: Rt = R1 + R2 + R3. 300Ω / 3 = 100Ω.
Which equation correctly calculates total resistance for two parallel resistors
(R1 and R2)?
A) R1 + R2
B) 1/R1 + 1/R2
C) (R1 × R2) / (R1 + R2)
D) (R1 + R2) / (R1 × R2)
Answer: C
, 4. Rationale: The product-over-sum rule is the standard shortcut for two
parallel resistors.
A Battery Management System (BMS) primarily prevents what condition in
lithium-ion packs?
A) Overvoltage and undervoltage
B) Short circuits in the load
C) RF interference
D) AC ripple
Answer: A
5. Rationale: 2026 BMS updates emphasize cell balancing and protection
against overcharge/over-discharge to prevent thermal runaway.
According to Kirchhoff's Voltage Law (KVL), the sum of voltages around a closed
loop is:
A) Equal to the current
B) Zero
C) Equal to the largest resistance
D) Infinite
Answer: B
6. Rationale: KVL states the algebraic sum of all voltages in a closed loop
equals zero.
What is the current through a 4Ω resistor if the voltage drop across it is 20V?
A) 5A
B) 80A
C) 16A
D) 0.2A
Answer: A
7. Rationale: I = V/R = 20/4 = 5A.
How should an ammeter be connected in a circuit?
A) In parallel
B) In series
C) Across the load
D) With the power off only
Answer: B
, 8. Rationale: Ammeters measure current and must be in series to ensure all
current flows through the meter.
A circuit has a 10V source and two 5Ω resistors in series. What is the voltage
drop across one resistor?
A) 10V
B) 2.5V
C) 5V
D) 7.5V
Answer: C
9. Rationale: Series circuit current is 10V/10Ω = 1A. Voltage drop = 1A × 5Ω =
5V. It acts as a voltage divider.
Energy efficiency in a DC-DC converter is calculated as:
A) Pout / Pin
B) Pin / Pout
C) Pin - Pout
D) Pin + Pout
Answer: A
10.Rationale: Efficiency (η) is the ratio of useful output power to total input
power.
What is the maximum power transfer theorem condition?
A) Load resistance equals source resistance
B) Load resistance is zero
C) Load resistance is infinite
D) Source resistance is zero
Answer: A
11. Rationale: Maximum power is transferred to the load when RL = RS.
Which meter setting measures continuity?
A) DC Volts
B) AC Amps
C) Ohms / Diode test
D) Frequency
Answer: C
12.Rationale: Ohms setting checks for a low-resistance path (continuity).
Three 12Ω resistors are connected in parallel. Total resistance is:
, A) 36Ω
B) 4Ω
C) 6Ω
D) 12Ω
Answer: B
13.Rationale: 1/Rt = 1/12 + 1/12 + 1/12 = 3/12. Rt = 12/3 = 4Ω.
A potentiometer has three terminals. It is primarily used as a:
A) Fixed resistor
B) Voltage divider
C) Current limiter
D) Capacitor
Answer: B
14.Rationale: The wiper sliding across the resistive element creates an
adjustable voltage divider.
If power is 50W and voltage is 120V, what is the resistance?
A) 2.4Ω
B) 288Ω
C) 6000Ω
D) 0.4Ω
Answer: B
15.Rationale: P = V²/R -> R = V²/P = (120²)/50 = 14400/50 = 288Ω.
An open circuit in a series network will cause:
A) Total current to drop slightly
B) Total current to become zero
C) Total voltage to drop to zero
D) Resistance to decrease
Answer: B
16.Rationale: An open breaks the current path; I = 0.
Kirchhoff's Current Law (KCL) states that current entering a node equals:
A) Voltage leaving the node
B) Current leaving the node
C) Resistance at the node
D) Power at the node
Answer: B
