WTMA Basic Electrical Principles 4 โ Questions and Answers
Question 1: Which direction does conventional current flow in a circuit?
- From positive terminal to negative terminal (Correct answer)
- From negative terminal to positive terminal
- In both directions at once
- Only through insulators
Correct answer: From positive terminal to negative terminal
By convention, current is defined as flowing from the positive terminal through the external circuit to the negative terminal.
Question 2: What component stores electrical charge in a circuit?
- Capacitor (Correct answer)
- Resistor
- Diode
- Transformer
Correct answer: Capacitor
A capacitor stores electrical energy as an electric field between two conductive plates separated by an insulator.
Question 3: Three 9-ohm resistors are connected in parallel. What is the total resistance?
- 3 ohms (Correct answer)
- 27 ohms
- 9 ohms
- 1 ohm
Correct answer: 3 ohms
For identical resistors in parallel, total resistance = R/n = 9 ฮฉ รท 3 = 3 ohms.
Question 4: What is the primary purpose of a ground wire in an electrical system?
- To provide a safe path for fault current and prevent shock (Correct answer)
- To increase circuit voltage
- To add resistance to the circuit
- To store extra charge
Correct answer: To provide a safe path for fault current and prevent shock
A ground wire provides a low-resistance return path for fault current, protecting people from electric shock if a fault occurs.
Question 5: What happens to the brightness of bulbs in a series circuit as more bulbs are added?
- Each bulb gets dimmer (Correct answer)
- Each bulb gets brighter
- Brightness stays the same
- Only the first bulb dims
Correct answer: Each bulb gets dimmer
Adding bulbs in series increases total resistance, reducing current through all bulbs, which makes each one dimmer.
Question 6: Alternating current (AC) differs from direct current (DC) because AC:
- Reverses direction periodically (Correct answer)
- Only flows in one direction
- Cannot power motors
- Has no voltage
Correct answer: Reverses direction periodically
AC periodically reverses its direction of flow, cycling back and forth, while DC flows continuously in one direction.
Question 7: A circuit has a 9-volt battery and a resistor. If 0.5 amperes flow, what is the resistance?
- 18 ohms (Correct answer)
- 4.5 ohms
- 9.5 ohms
- 0.055 ohms
Correct answer: 18 ohms
Using Ohm's Law: R = V/I = 9 V รท 0.5 A = 18 ohms.
WTMA Basic Electrical Principles 4
Which direction does conventional current flow in a circuit?