Polytechnic Electronics and Electrical Engineering 2 — Questions and Answers
Question 1: What does AC stand for in electrical engineering?
- Amplified Current
- Alternating Current (Correct answer)
- Automatic Control
- Applied Circuit
Correct answer: Alternating Current
AC stands for Alternating Current, where the direction of current flow reverses periodically.
Question 2: Kirchhoff's Current Law (KCL) states that:
- Voltage around a closed loop equals zero
- The sum of currents entering a node equals the sum leaving it (Correct answer)
- Resistance increases with temperature
- Power equals voltage times time
Correct answer: The sum of currents entering a node equals the sum leaving it
KCL states that the algebraic sum of all currents at a node is zero, meaning current in equals current out.
Question 3: What is the capacitance of a capacitor that stores 0.01 coulombs of charge at 5 volts?
- 0.0005 F
- 0.002 F (Correct answer)
- 0.05 F
- 50 F
Correct answer: 0.002 F
C = Q/V = 0.01/5 = 0.002 F (2 millifarads), using the capacitance formula.
Question 4: An NPN transistor is in saturation mode when:
- Both junctions are reverse-biased
- The base-emitter junction is forward-biased and base-collector is reverse-biased
- Both junctions are forward-biased (Correct answer)
- No base current is applied
Correct answer: Both junctions are forward-biased
In saturation, both the base-emitter and base-collector junctions are forward-biased, fully turning on the transistor.
Question 5: What is the purpose of a voltage divider circuit?
- To increase current in a branch
- To produce a lower output voltage from a higher input voltage (Correct answer)
- To store electrical energy
- To convert AC to DC
Correct answer: To produce a lower output voltage from a higher input voltage
A voltage divider uses two resistors in series to produce an output voltage that is a fraction of the input voltage.
Question 6: What does an ammeter measure and how is it connected in a circuit?
- Voltage; connected in parallel
- Resistance; connected in series
- Current; connected in series (Correct answer)
- Power; connected in parallel
Correct answer: Current; connected in series
An ammeter measures current and must be connected in series so the full circuit current flows through it.
Question 7: Which logic gate outputs HIGH only when all inputs are HIGH?
- OR gate
- AND gate (Correct answer)
- NAND gate
- NOR gate
Correct answer: AND gate
An AND gate outputs HIGH (1) only when all of its inputs are HIGH (1), implementing logical conjunction.
Polytechnic Electronics and Electrical Engineering 2
What does AC stand for in electrical engineering?