ATT Test 2 – Comprehensive Illustrated Exam &
Study Guide with Answers, Rationales, and Visual
Diagrams | 2025 Edition | Complete Practice &
Review for Mastery”
1. What is the main function of a transistor in electronics?
A) Store energy
B) Amplify or switch signals
C) Convert AC to DC
D) Limit current
Answer: B) Amplify or switch signals
Rationale: Transistors can control large currents with a small input signal and act as switches.
2. A PNP transistor conducts when:
A) Base is positive relative to emitter
B) Base is negative relative to emitter
C) Collector is positive relative to emitter
D) Emitter is negative relative to collector
Answer: B) Base is negative relative to emitter
Rationale: PNP transistors conduct when the base is sufficiently negative to the emitter.
3. Which logic gate outputs HIGH only if both inputs are HIGH?
A) OR
B) AND
C) NAND
D) XOR
Answer: B) AND
Rationale: AND gate logic: Output = 1 only when all inputs = 1.
4. Which logic gate outputs LOW only if both inputs are HIGH?
,A) OR
B) AND
C) NAND
D) XOR
Answer: C) NAND
Rationale: NAND is the complement of AND; LOW only when inputs are both HIGH.
5. In digital electronics, a flip-flop is used for:
A) Voltage conversion
B) Signal amplification
C) Data storage
D) Current limiting
Answer: C) Data storage
Rationale: Flip-flops store a single bit of digital data (0 or 1).
6. What is the main purpose of an operational amplifier (Op-Amp)?
A) Measure resistance
B) Amplify voltage
C) Convert AC to DC
D) Act as a diode
Answer: B) Amplify voltage
Rationale: Op-Amps provide high-gain voltage amplification for analog signals.
7. Which semiconductor device allows current flow in both directions but
controls it using a gate?
A) SCR
B) Triac
C) Diode
D) MOSFET
Answer: B) Triac
Rationale: Triacs conduct AC in both directions when the gate is triggered.
8. What is the characteristic of a Schottky diode?
, A) High voltage drop
B) Low forward voltage drop and fast switching
C) Only used in AC circuits
D) Acts like a fuse
Answer: B) Low forward voltage drop and fast switching
Rationale: Schottky diodes are ideal for high-speed, low-voltage applications.
9. A 5 V logic circuit receives 10 mA current. What is the power consumed?
A) 0.05 W
B) 0.1 W
C) 0.5 W
D) 1 W
Answer: B) 0.05 W
Rationale: P = V × I → P = 5 × 0.01 = 0.05 W.
10. What does an SCR (Silicon Controlled Rectifier) do?
A) Amplifies signals
B) Acts as a controlled switch for high current
C) Stores energy
D) Reduces voltage
Answer: B) Acts as a controlled switch for high current
Rationale: SCRs allow current flow only when a gate trigger is applied.
11. Which logic gate is represented by the equation Y = A + B?
A) AND
B) OR
C) XOR
D) NAND
Answer: B) OR
Rationale: OR gate outputs HIGH if any input is HIGH.
12. In a common-emitter transistor amplifier, the output is:
A) In-phase with input
B) 180° out-of-phase with input
Study Guide with Answers, Rationales, and Visual
Diagrams | 2025 Edition | Complete Practice &
Review for Mastery”
1. What is the main function of a transistor in electronics?
A) Store energy
B) Amplify or switch signals
C) Convert AC to DC
D) Limit current
Answer: B) Amplify or switch signals
Rationale: Transistors can control large currents with a small input signal and act as switches.
2. A PNP transistor conducts when:
A) Base is positive relative to emitter
B) Base is negative relative to emitter
C) Collector is positive relative to emitter
D) Emitter is negative relative to collector
Answer: B) Base is negative relative to emitter
Rationale: PNP transistors conduct when the base is sufficiently negative to the emitter.
3. Which logic gate outputs HIGH only if both inputs are HIGH?
A) OR
B) AND
C) NAND
D) XOR
Answer: B) AND
Rationale: AND gate logic: Output = 1 only when all inputs = 1.
4. Which logic gate outputs LOW only if both inputs are HIGH?
,A) OR
B) AND
C) NAND
D) XOR
Answer: C) NAND
Rationale: NAND is the complement of AND; LOW only when inputs are both HIGH.
5. In digital electronics, a flip-flop is used for:
A) Voltage conversion
B) Signal amplification
C) Data storage
D) Current limiting
Answer: C) Data storage
Rationale: Flip-flops store a single bit of digital data (0 or 1).
6. What is the main purpose of an operational amplifier (Op-Amp)?
A) Measure resistance
B) Amplify voltage
C) Convert AC to DC
D) Act as a diode
Answer: B) Amplify voltage
Rationale: Op-Amps provide high-gain voltage amplification for analog signals.
7. Which semiconductor device allows current flow in both directions but
controls it using a gate?
A) SCR
B) Triac
C) Diode
D) MOSFET
Answer: B) Triac
Rationale: Triacs conduct AC in both directions when the gate is triggered.
8. What is the characteristic of a Schottky diode?
, A) High voltage drop
B) Low forward voltage drop and fast switching
C) Only used in AC circuits
D) Acts like a fuse
Answer: B) Low forward voltage drop and fast switching
Rationale: Schottky diodes are ideal for high-speed, low-voltage applications.
9. A 5 V logic circuit receives 10 mA current. What is the power consumed?
A) 0.05 W
B) 0.1 W
C) 0.5 W
D) 1 W
Answer: B) 0.05 W
Rationale: P = V × I → P = 5 × 0.01 = 0.05 W.
10. What does an SCR (Silicon Controlled Rectifier) do?
A) Amplifies signals
B) Acts as a controlled switch for high current
C) Stores energy
D) Reduces voltage
Answer: B) Acts as a controlled switch for high current
Rationale: SCRs allow current flow only when a gate trigger is applied.
11. Which logic gate is represented by the equation Y = A + B?
A) AND
B) OR
C) XOR
D) NAND
Answer: B) OR
Rationale: OR gate outputs HIGH if any input is HIGH.
12. In a common-emitter transistor amplifier, the output is:
A) In-phase with input
B) 180° out-of-phase with input
