CEA Basic Electrical Theory Questions and Answers — Questions and Answers
Question 1: An electrical apprentice is tasked with calculating the current in a simple DC circuit. The circuit has a voltage of 12 volts and a total resistance of 4 ohms. According to Ohm's Law, what is the current flowing through this circuit?
- 48 Amperes
- 0.33 Amperes
- 16 Amperes
- 3 Amperes (Correct answer)
Correct answer: 3 Amperes
Ohm's Law states that Current (I) = Voltage (V) / Resistance (R). In this scenario, I = 12V / 4Ω, which equals 3 Amperes.
Question 2: In a series circuit, if one of three light bulbs burns out, what happens to the other two bulbs?
- They become brighter.
- They all go out. (Correct answer)
- They remain lit with the same brightness.
- They become dimmer.
Correct answer: They all go out.
In a series circuit, there is only one path for the current to flow. If one bulb burns out, the path is broken, and the entire circuit is opened, causing all the bulbs to go out.
Question 3: Which of the following statements is true for a parallel circuit?
- The total resistance is the sum of all individual resistances.
- The current is the same through all components.
- The voltage is the same across all components. (Correct answer)
- If one component fails, the entire circuit stops working.
Correct answer: The voltage is the same across all components.
A key characteristic of a parallel circuit is that the voltage is constant across all components connected in parallel. The total current is divided among the branches, and the total resistance is less than the smallest individual resistance.
Question 4: An apprentice measures the opposition to current flow in a circuit. What is this property called, and what unit is it measured in?
- Voltage, measured in Volts (V)
- Current, measured in Amperes (A)
- Power, measured in Watts (W)
- Resistance, measured in Ohms (Ω) (Correct answer)
Correct answer: Resistance, measured in Ohms (Ω)
Resistance is the measure of the opposition to current flow in an electrical circuit. It is measured in units called Ohms (Ω).
Question 5: A senior electrician asks an apprentice to calculate the total resistance of a circuit containing two resistors connected in parallel. The resistors have values of 10 ohms and 20 ohms. What is the approximate total resistance?
- 30 ohms
- 6.67 ohms (Correct answer)
- 15 ohms
- 10 ohms
Correct answer: 6.67 ohms
The formula for calculating the total resistance (Rt) of two resistors in parallel is Rt = (R1 * R2) / (R1 + R2). Therefore, Rt = (10 * 20) / (10 + 20) = 200 / 30 ≈ 6.67 ohms. The total resistance in a parallel circuit is always less than the smallest individual resistor.
Question 6: What is the primary difference between Alternating Current (AC) and Direct Current (DC)?
- DC flows in one direction, while AC periodically changes direction. (Correct answer)
- AC is only used in low-voltage applications, while DC is for high-voltage.
- DC is generated by power plants, while AC is supplied by batteries.
- AC has a constant voltage, while DC voltage varies.
Correct answer: DC flows in one direction, while AC periodically changes direction.
Direct Current (DC) is the flow of electric charge in only one direction. Alternating Current (AC) is the flow of electric charge that periodically reverses direction.
CEA Basic Electrical Theory Questions and Answers
An electrical apprentice is tasked with calculating the current in a simple DC circuit.
The circuit has a voltage of 12 volts and a total resistance of 4 ohms.
According to Ohm's Law, what is the current flowing through this circuit?