Introduction to Electrical Engineering MCQs (Part-5)
What does Kirchhoff’s Current Law state?
A Resistance is constant
B Current is conserved
C Voltage is constant
D Power is conserved
Kirchhoff’s Current Law (KCL) states that the sum of currents entering a junction in a circuit must equal the sum of currents leaving the junction. This law is based on the conservation of electric charge.
What is the SI unit of electrical energy?
A Joule
B Volt
C Ampere
D Watt
The SI unit of electrical energy is the Joule (J). It represents the amount of energy transferred when one ampere of current flows through a resistance of one ohm for one second.
What does the power formula P=I²R calculate?
A Resistance
B Voltage
C Power
D Current
The formula P=I²R calculates electrical power dissipated in a resistor. Power is the product of the square of current (I) and resistance (R), showing how much energy is lost as heat.
What happens to current when resistance is doubled while keeping voltage constant?
A Quadruples
B Doubles
C Stays the same
D Halves
According to Ohm’s Law, current is inversely proportional to resistance. Doubling the resistance while keeping voltage constant will halve the current, as I = V / R.
What does the formula P=V²/R calculate?
A Resistance
B Power
C Voltage
D Current
The formula P=V²/R calculates electrical power dissipated in a resistor. It shows how power increases with voltage and decreases with resistance, which is useful for power calculations in circuits.
What is the unit of electric charge?
A Watt
B Volt
C Coulomb
D Ampere
The unit of electric charge is the Coulomb (C). One Coulomb is the amount of charge transported by a current of one ampere flowing for one second. It is a fundamental unit in electromagnetism.
Which of the following is a property of resistors in a circuit?
A Limit current flow
B Measure current
C Increase voltage
D Store energy
Resistors limit the flow of electric current in a circuit. By providing opposition to current, they control the flow of electricity and ensure that other components receive the correct amount of current.
What does a transformer do?
A Increase current
B Change voltage
C Increase resistance
D Store energy
A transformer is used to change the voltage level in an AC circuit. It can either step up or step down the voltage, which is essential for efficient long-distance power transmission and adapting to device needs.
What is the function of a diode in an electrical circuit?
A Convert energy to light
B Allow current flow in one direction
C Measure resistance
D Store energy
A diode allows current to flow in only one direction, acting as a one-way valve for electricity. It is often used in power supplies to convert AC to DC by blocking the reverse current.
What is the purpose of an electrical capacitor?
A Store energy
B Block current
C Store voltage
D Measure current
A capacitor stores electrical energy in an electric field between two conductive plates. It can release the stored energy when needed, making it useful for filtering and smoothing voltage fluctuations in circuits.
Which material is a good conductor of electricity?
A Plastic
B Wood
C Copper
D Rubber
Copper is an excellent conductor of electricity because of its low resistance. It allows electric charges to flow freely, making it the material of choice for electrical wiring in homes and industrial applications.
What is the function of a circuit breaker?
A Increase current flow
B Break the circuit in case of overload
C Measure voltage
D Store energy
A circuit breaker is a safety device that automatically breaks a circuit when it detects an overload or short circuit. This prevents electrical fires and damage to equipment by interrupting the current flow.
What does an inductor do in a circuit?
A Convert energy to light
B Store current
C Measure resistance
D Store energy in a magnetic field
An inductor stores energy in a magnetic field when current flows through it. It resists changes in the current and can release the stored energy when required, making it useful in filtering and inductive applications.
What is the primary function of a voltage source in a circuit?
A Store energy
B Limit current
C Provide voltage to the circuit
D Control current flow
A voltage source, such as a battery or power supply, provides electrical energy to a circuit by creating a potential difference (voltage) that drives the flow of current through the circuit.
What happens to the total resistance in a series circuit?
A It increases
B It decreases
C It remains constant
D It fluctuates
In a series circuit, the total resistance is the sum of all individual resistances. As more resistors are added in series, the total resistance increases, which reduces the current flow through the circuit.