CEA Electrical Theory & Fundamentals — Questions and Answers
Question 1: What is Ohm’s Law?
- Voltage equals current times resistance (Correct answer)
- Current equals voltage divided by power
- Resistance equals voltage times current
- Power equals voltage minus current
Correct answer: Voltage equals current times resistance
Ohm's Law is a fundamental principle in electrical engineering that describes the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit. It states that the voltage across a conductor is directly proportional to the current flowing through it, given by the formula V = I × R. This law is crucial for understanding and calculating electrical circuit behavior.
Question 2: Which unit is used to measure electrical resistance?
- Ampere
- Ohm (Correct answer)
- Volt
- Watt
Correct answer: Ohm
The Ohm (Ω) is the standard unit of electrical resistance, named after Georg Simon Ohm. Resistance is a measure of how much an object or material opposes the flow of electric current. Other units like Ampere measure current, Volt measures voltage, and Watt measures power.
Question 3: What does a capacitor do in an electrical circuit?
- Stores electrical charge (Correct answer)
- Resists current flow
- Increases voltage
- Measures current
Correct answer: Stores electrical charge
A capacitor is a passive electronic component designed to store electrical energy in an electric field. It consists of two conductive plates separated by a dielectric material. When a voltage is applied, charge accumulates on the plates, allowing the capacitor to store and then release this energy, often used for filtering or timing in circuits.
Question 4: What is the function of a transformer?
- Converts AC to DC
- Changes voltage levels in AC (Correct answer)
- Measures resistance
- Stores electrical energy
Correct answer: Changes voltage levels in AC
A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. Its primary function is to change voltage levels in alternating current (AC) circuits, either stepping up (increasing) or stepping down (decreasing) the voltage. This capability is crucial for efficient power transmission and distribution.
Question 5: Which component opposes changes in current flow?
- Resistor
- Capacitor
- Inductor (Correct answer)
- Transformer
Correct answer: Inductor
An inductor is a passive electrical component that stores energy in a magnetic field when electric current flows through it. Its primary characteristic, inductance, causes it to oppose changes in the current flowing through it. This property is utilized in many circuits for filtering, energy storage, and tuning.
Question 6: What type of current reverses direction periodically?
- Direct Current (DC)
- Alternating Current (AC) (Correct answer)
- Static Current
- Continuous Current
Correct answer: Alternating Current (AC)
Alternating Current (AC) is an electric current that periodically reverses its direction of flow, unlike Direct Current (DC) which flows in only one direction. AC is the standard form of electricity delivered to homes and businesses because it can be efficiently transmitted over long distances and its voltage easily transformed using transformers.
Question 7: Which formula calculates electrical power?
- Power = Voltage × Current (Correct answer)
- Power = Resistance ÷ Current
- Power = Current − Voltage
- Power = Voltage + Resistance
Correct answer: Power = Voltage × Current
Electrical power (P) is the rate at which electrical energy is transferred or consumed in a circuit. It is calculated by multiplying the voltage (V) across a component by the current (I) flowing through it, expressed by the formula P = V × I. This formula is fundamental for determining energy consumption and designing electrical systems.
Question 8: What safety device protects a circuit from overload?
- Fuse
- Circuit Breaker (Correct answer)
- Resistor
- Capacitor
Correct answer: Circuit Breaker
A circuit breaker is an automatic electrical safety switch designed to protect an electrical circuit from damage caused by an overload or short circuit. When an excessive current is detected, it automatically interrupts the flow of electricity, preventing overheating, wire damage, and potential fires. Unlike fuses, circuit breakers can be reset after tripping.
Question 9: What is the unit of electrical current?
- Volt
- Ampere (Correct answer)
- Ohm
- Watt
Correct answer: Ampere
The Ampere (A), often shortened to 'amp,' is the SI unit of electric current. It measures the rate of flow of electric charge through a conductor. A Volt measures electrical potential difference (voltage), an Ohm measures electrical resistance, and a Watt measures electrical power.
CEA Electrical Theory & Fundamentals
What is Ohm’s Law?