What is the primary function of a transformer in an electrical circuit?
A To store energy
B To limit current
C To change voltage
D To measure power
A transformer is used to either increase or decrease the voltage in an AC circuit, depending on the turns ratio of its coils. It operates based on the principle of electromagnetic induction without changing the frequency of the current.
What type of current does a transformer work with?
A Alternating current (AC)
B Direct current (DC)
C Both DC and AC
D Pulsating current
A transformer only works with alternating current (AC) because it relies on the changing magnetic field created by the alternating current to induce voltage in the secondary coil. It does not work with DC.
Which device protects an electrical circuit from excessive current?
A Resistor
B Capacitor
C Inductor
D Fuse
A fuse is a safety device that protects circuits from excessive current by melting when the current exceeds a specified limit. This interrupts the circuit, preventing damage to the components from overloads or short circuits.
What is the function of a circuit breaker?
A Store energy
B Interrupt overcurrent
C Measure current
D Change voltage
A circuit breaker is a safety device designed to interrupt the current flow in a circuit when an overcurrent occurs. It can be reset after tripping, unlike a fuse, which must be replaced once it blows.
What is the purpose of grounding an electrical system?
A Control current
B Increase voltage
C Prevent electric shock
D Store charge
Grounding provides a safe path for stray electrical current to flow into the earth, preventing electric shocks. It ensures that the exposed metal parts of electrical devices do not carry dangerous voltages.
Which component is used to measure the electrical potential difference between two points?
A Voltmeter
B Ammeter
C Ohmmeter
D Wattmeter
A voltmeter is used to measure the voltage or potential difference between two points in an electrical circuit. It is connected in parallel with the component whose voltage is to be measured.
What is the most common use of a capacitor in an electrical circuit?
A Limit voltage
B Store energy
C Change current
D Measure resistance
A capacitor stores energy in an electric field when charged. It is used in circuits for filtering, smoothing voltage fluctuations, and in power supply systems to temporarily store electrical energy for later use.
What happens to the total resistance in a parallel circuit?
A It increases
B It stays the same
C It is zero
D It decreases
In a parallel circuit, the total resistance decreases as more components are added. The reciprocal of the total resistance is the sum of the reciprocals of the individual resistances. This leads to a lower overall resistance.
Which of the following units measures electrical power?
A Ampere
B Volt
C Watt
D Ohm
Watt (W) is the unit of electrical power. Power is the rate at which electrical energy is transferred or converted. It is calculated as the product of voltage and current (P = V × I).
Which electrical device is used to store electrical charge temporarily?
A Inductor
B Capacitor
C Resistor
D Battery
A capacitor stores electrical charge in an electric field between two conductive plates. It temporarily holds energy and can discharge it when needed, making it useful in circuits for smoothing voltage and energy storage.
What is the purpose of a diode in a circuit?
A Convert AC to DC
B Limit voltage
C Store energy
D Measure current
A diode is used to convert alternating current (AC) to direct current (DC). It allows current to flow in one direction only, thereby rectifying AC to DC, which is essential for powering many electronic devices.
Which type of electrical circuit allows current to flow through multiple paths?
A Series circuit
B Open circuit
C Parallel circuit
D Short circuit
A parallel circuit provides multiple paths for the current to flow. If one component fails, the others remain functional. The voltage across all components in a parallel circuit is the same.
What is the effect of increasing the resistance in a circuit?
A Increases voltage
B Increases current
C No effect
D Decreases current
According to Ohm’s Law (V = IR), increasing the resistance in a circuit will decrease the current, assuming the voltage remains constant. Higher resistance makes it harder for current to flow through the circuit.
Which of the following components is used to store electrical energy in a magnetic field?
A Capacitor
B Inductor
C Battery
D Fuse
An inductor stores electrical energy in the form of a magnetic field created by the current flowing through it. It resists changes in current and releases energy when the current decreases. Inductors are used in many electrical devices, including transformers and motors.
What is the unit of electric current?
A Ampere
B Watt
C Volt
D Ohm
The unit of electric current is the ampere (A). It measures the flow of electric charge in a circuit. One ampere is defined as the flow of one coulomb of charge per second.