CEA - Certified Electrical Apprentice Basic Electrical Theory Questions and Answers — Questions and Answers
Question 1: According to Ohm's Law, what happens to the current in a circuit if the voltage is doubled while the resistance remains constant?
- It is halved.
- It is doubled. (Correct answer)
- It remains the same.
- It becomes zero.
Correct answer: It is doubled.
Ohm's Law states that current (I) is directly proportional to voltage (V) and inversely proportional to resistance (R), expressed as I = V/R. Therefore, if the voltage is doubled and resistance stays the same, the current must also double to maintain the relationship.
Question 2: An apprentice is tasked with wiring a circuit containing three resistors. If the goal is to have the same voltage across each resistor, which type of circuit configuration should be used?
- A series circuit
- A parallel circuit (Correct answer)
- A series-parallel circuit
- An open circuit
Correct answer: A parallel circuit
In a parallel circuit, all components are connected across the same two points, meaning the voltage across each branch is the same as the source voltage. In a series circuit, the current is the same through all components, but the voltage is divided among them.
Question 3: Which of the following materials is considered a good electrical insulator?
- Copper
- Aluminum
- Silver
- Rubber (Correct answer)
Correct answer: Rubber
Insulators are materials that have high electrical resistivity and do not allow electrons to move freely. Rubber, plastic, and glass are common examples used to prevent the flow of current. Copper, aluminum, and silver are excellent conductors because their electrons are loosely bound.
Question 4: A 120-volt circuit powers a heater with a resistance of 12 ohms. How much power does the heater consume?
- 10 watts
- 1440 watts
- 1200 watts (Correct answer)
- 12 watts
Correct answer: 1200 watts
The formula for electrical power (P) is P = V^2 / R, where V is voltage and R is resistance. In this scenario, P = (120V)^2 / 12Ω. So, P = 14400 / 12, which equals 1200 watts.
Question 5: In a simple series circuit, what is the total resistance if it contains three resistors with values of 10Ω, 20Ω, and 30Ω?
- 10Ω
- 60Ω (Correct answer)
- 5.45Ω
- 110Ω
Correct answer: 60Ω
For resistors connected in series, the total resistance is the sum of the individual resistances. Therefore, R_total = R1 + R2 + R3 = 10Ω + 20Ω + 30Ω = 60Ω.
Question 6: The flow of electrons through a conductor is known as:
- Voltage
- Resistance
- Current (Correct answer)
- Power
Correct answer: Current
Electric current is defined as the rate of flow of electric charge, which in a metallic conductor is the movement of free electrons. Voltage is the electrical pressure that causes the current to flow, and resistance is the opposition to that flow.
CEA - Certified Electrical Apprentice Basic Electrical Theory Questions and Answers
According to Ohm's Law, what happens to the current in a circuit if the voltage is doubled while the resistance remains constant?