ATT TECHNICAL APTITUDE TEST 3
QUESTIONS AND ANSWERS 2026
1. In a parallel circuit with three resistors of 10, 20, and 30 ohms respectively, what is the
total equivalent resistance?
A. 5.45 ohms
B. 60.00 ohms
C. 20.00 ohms
D. 0.18 ohms
Answer: A
Conceptual Explanation: The formula for parallel resistance is 1/Rt = 1/R1 + 1/R2 +
1/R3. Here, 1/Rt = 1/10 + 1/20 + 1/30 = 0.1 + 0.05 + 0.0333 = 0.1833. Rt = .1833 ≈
5.45 ohms.
2. Which layer of the OSI model is responsible for logical addressing and routing?
A. Data Link Layer
B. Network Layer
C. Transport Layer
,D. Physical Layer
Answer: B
Conceptual Explanation: The Network Layer (Layer 3) handles IP addressing and
determines the best path for data through routing protocols.
3. What is the primary cause of ‘chromatic dispersion’ in fiber optic cables?
A. Imperfections in the fiber core geometry
B. Different wavelengths of light traveling at different speeds
C. Light leaking out of the cladding
D. Reflection at the connector interface
Answer: B
Conceptual Explanation: Chromatic dispersion occurs because different spectral
components (colors/wavelengths) of a light pulse travel at different velocities in a fiber.
4. In digital logic, which gate produces a high output (1) only when an odd number of inputs
are high?
A. NAND Gate
B. OR Gate
C. XOR Gate
D. AND Gate
, Answer: C
Conceptual Explanation: The XOR (Exclusive OR) gate acts as an odd-parity generator,
returning 1 if the number of 1s at the input is odd.
5. What is the phase shift between voltage and current in a purely inductive AC circuit?
A. Voltage leads current by 180 degrees
B. Current leads voltage by 90 degrees
C. Voltage and current are in phase
D. Voltage leads current by 90 degrees
Answer: D
Conceptual Explanation: In an inductor, the current lags the voltage by 90 degrees, or the
voltage leads the current by 90 degrees (ELI acronym).
6. A signal experiences a loss of 30 dB. What fraction of the original power remains?
A. 1/3
B. 1/30
C. 1/100
D. 1/1000
Answer: D
QUESTIONS AND ANSWERS 2026
1. In a parallel circuit with three resistors of 10, 20, and 30 ohms respectively, what is the
total equivalent resistance?
A. 5.45 ohms
B. 60.00 ohms
C. 20.00 ohms
D. 0.18 ohms
Answer: A
Conceptual Explanation: The formula for parallel resistance is 1/Rt = 1/R1 + 1/R2 +
1/R3. Here, 1/Rt = 1/10 + 1/20 + 1/30 = 0.1 + 0.05 + 0.0333 = 0.1833. Rt = .1833 ≈
5.45 ohms.
2. Which layer of the OSI model is responsible for logical addressing and routing?
A. Data Link Layer
B. Network Layer
C. Transport Layer
,D. Physical Layer
Answer: B
Conceptual Explanation: The Network Layer (Layer 3) handles IP addressing and
determines the best path for data through routing protocols.
3. What is the primary cause of ‘chromatic dispersion’ in fiber optic cables?
A. Imperfections in the fiber core geometry
B. Different wavelengths of light traveling at different speeds
C. Light leaking out of the cladding
D. Reflection at the connector interface
Answer: B
Conceptual Explanation: Chromatic dispersion occurs because different spectral
components (colors/wavelengths) of a light pulse travel at different velocities in a fiber.
4. In digital logic, which gate produces a high output (1) only when an odd number of inputs
are high?
A. NAND Gate
B. OR Gate
C. XOR Gate
D. AND Gate
, Answer: C
Conceptual Explanation: The XOR (Exclusive OR) gate acts as an odd-parity generator,
returning 1 if the number of 1s at the input is odd.
5. What is the phase shift between voltage and current in a purely inductive AC circuit?
A. Voltage leads current by 180 degrees
B. Current leads voltage by 90 degrees
C. Voltage and current are in phase
D. Voltage leads current by 90 degrees
Answer: D
Conceptual Explanation: In an inductor, the current lags the voltage by 90 degrees, or the
voltage leads the current by 90 degrees (ELI acronym).
6. A signal experiences a loss of 30 dB. What fraction of the original power remains?
A. 1/3
B. 1/30
C. 1/100
D. 1/1000
Answer: D
