Introduction to Electrical Engineering MCQs (Part-3)
What is the role of a transformer in an electrical system?
A Step up or step down voltage
B Convert AC to DC
C Store electrical energy
D Measure current
A transformer is used to increase (step-up) or decrease (step-down) voltage levels in an AC system. It operates on the principle of electromagnetic induction.
What is the primary purpose of a capacitor in a circuit?
A Measure current
B Generate electrical energy
C Block current flow
D Store electrical energy
A capacitor stores electrical energy in an electric field. It consists of two conductive plates separated by an insulator and is used in circuits for energy storage, filtering, and timing applications.
Which of the following is a characteristic of a DC system?
A Current changes direction
B Frequency is 50 Hz
C Voltage is constant
D Used in transformers
In a DC (Direct Current) system, the voltage remains constant over time, and the current flows in a single direction, unlike AC (Alternating Current), where both voltage and current change direction periodically.
What is the function of a diode in a circuit?
A Amplify signals
B Allow current in one direction
C Store energy
D Measure voltage
A diode is a semiconductor device that allows current to flow in one direction only. It is commonly used for rectification, converting AC to DC.
What is the unit of electrical energy?
A Volt
B Joule
C Ampere
D Ohm
The unit of electrical energy is the Joule (J). It represents the amount of work done when a force of one Newton moves an object one meter. In electrical terms, it is the energy consumed when one Ampere flows through one Ohm for one second.
What is the unit of electric potential?
A Watt
B Ampere
C Ohm
D Volt
The unit of electric potential is the Volt (V). It represents the potential energy per unit charge and is a measure of the work done to move a charge between two points.
What is the SI unit of electric charge?
A Coulomb
B Volt
C Ampere
D Ohm
The SI unit of electric charge is the Coulomb (C). It represents the quantity of electricity transported by a current of one Ampere in one second.
What is the relationship between power, voltage, and current?
A P = V^2 / I
B P = V I
C P = V / I^2
D P = V / I
The relationship between power (P), voltage (V), and current (I) is given by P = V I. Power is the product of voltage and current and is measured in watts.
Which law describes the force between two electric charges?
A Ohm’s Law
B Faraday’s Law
C Kirchhoff’s Law
D Coulomb’s Law
Coulomb’s Law describes the electrostatic force between two charged objects. It states that the force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.
Which of the following is a characteristic of an AC system?
A Frequency is 50 Hz or 60 Hz
B Current flows in one direction
C Voltage is constant
D Used in batteries
In an AC (Alternating Current) system, the voltage and current change direction periodically. The frequency of this change is typically 50 Hz or 60 Hz, depending on the region.
Which of the following is a renewable energy source?
A Coal
B Wind energy
C Natural gas
D Nuclear energy
Wind energy is a renewable energy source that harnesses the kinetic energy of wind to generate electricity using wind turbines. It is sustainable and environmentally friendly.
Which of the following is a safety measure in electrical systems?
A Increasing voltage
B Using high resistance
C Grounding
D Using copper wires
Grounding is a safety measure that provides a path for excess electric current to flow into the earth, preventing electric shock, fires, and damage to equipment.
Which of the following is an example of an insulator?
A Rubber
B Copper
C Aluminum
D Silver
Rubber is an insulator because it has very high resistance and does not allow electric current to flow through it. It is commonly used to coat wires for safety.
Which device is used to measure electric current?
A Voltmeter
B Ohmmeter
C Ammeter
D Wattmeter
An ammeter is a device used to measure electric current in a circuit. It is connected in series with the circuit to measure the flow of current in amperes.
What is the primary function of a switch in a circuit?
A Store energy
B Generate power
C Control current flow
D Measure voltage
A switch is used to control the flow of current in a circuit by opening (breaking) or closing (completing) the circuit. It is a fundamental component in electrical systems.