What happens to the current in a circuit if the resistance is doubled while the voltage remains constant?
A Current doubles
B Current remains the same
C Current is halved
D Current becomes zero
According to Ohm’s Law, I = V/R. If R doubles, the current I is reduced to half while the voltage V remains constant.
Which device is used to step up or step down AC voltage?
A Generator
B Transformer
C Rectifier
D Motor
A transformer works on the principle of electromagnetic induction to increase (step-up) or decrease (step-down) the AC voltage.
What is the function of an Earth Leakage Circuit Breaker (ELCB)?
A To prevent overcurrent
B To detect ground faults
C To control voltage fluctuations
D To reduce resistance
ELCB detects leakage currents to the ground and disconnects the power supply to prevent electric shocks and fire hazards.
In a capacitor, the energy is stored in:
A Magnetic field
B Electric field
C Resistance
D Inductance
A capacitor stores energy in the form of an electric field created between its plates when a voltage is applied.
Which law states that the total current entering a junction equals the total current leaving it?
A Ohm’s Law
B Kirchhoff’s Current Law
C Faraday’s Law
D Lenz’s Law
Kirchhoff’s Current Law (KCL) states that the sum of currents entering a junction equals the sum of currents leaving it, ensuring charge conservation.
What is the primary purpose of a fuse in an electrical circuit?
A To measure current
B To regulate voltage
C To protect against overcurrent
D To store energy
A fuse protects a circuit by breaking the connection when the current exceeds a safe limit, preventing damage to devices and wiring.
What does an oscilloscope measure?
A Resistance
B Voltage over time
C Capacitance
D Magnetic field
An oscilloscope displays voltage signals as waveforms over time, helping analyze variations in AC and DC signals.
What is the purpose of a commutator in a DC motor?
A To generate power
B To reverse the direction of current
C To reduce resistance
D To step up voltage
The commutator reverses the current direction in the armature winding, ensuring continuous rotation of the DC motor.
What is the unit of electric power?
A Joule
B Watt
C Volt
D Ampere
Electric power is measured in watts (W). One watt equals one joule of energy consumed per second.
What is the main difference between a series circuit and a parallel circuit?
A Current is the same in all components of a series circuit
B Voltage is the same in all components of a series circuit
C Current is different in all components of a series circuit
D Voltage is different in all components of a parallel circuit
In a series circuit, the same current flows through all components because there is only one path for current flow.
What type of current does a battery produce?
A Alternating Current (AC)
B Direct Current (DC)
C Pulsating Current
D No current
A battery produces direct current (DC), where the flow of electric charge is unidirectional.
Which of the following is an ohmic conductor?
A Semiconductor
B Filament lamp
C Copper wire
D Diode
Ohmic conductors, like copper, follow Ohm’s Law, where the current is directly proportional to voltage, provided the temperature is constant.
What is the main disadvantage of an open circuit?
A Infinite resistance
B No current flow
C High power consumption
D Overcurrent
In an open circuit, there is a break in the connection, preventing current flow and rendering the circuit non-functional.
Which instrument is used to measure very high resistances?
A Ammeter
B Megger
C Voltmeter
D Multimeter
A megger is used to measure high resistances, typically in insulation testing of electrical equipment.
What is the primary role of an electric motor?
A To convert electrical energy into mechanical energy
B To convert mechanical energy into electrical energy
C To store energy
D To regulate voltage
An electric motor transforms electrical energy into mechanical energy, driving machines or devices like fans and pumps.
Which phenomenon is responsible for the working of an electric bell?
A Capacitance
B Electromagnetism
C Inductance
D Thermal effect
An electric bell uses electromagnetism to create a magnetic field, which moves a striker to hit the bell repeatedly.
What happens to the brightness of a bulb if its filament resistance increases?
A Brightness increases
B Brightness decreases
C Brightness remains the same
D The bulb explodes
As resistance increases, current decreases (by Ohm’s Law), resulting in reduced power and brightness.
What is the function of a rectifier in an electrical circuit?
A To amplify voltage
B To convert AC to DC
C To store charge
D To decrease resistance
A rectifier converts alternating current (AC) to direct current (DC) using diodes, making it suitable for devices requiring DC.
What causes a thermal effect in electrical circuits?
A Inductance
B Resistance
C Capacitance
D Voltage drop
The thermal effect occurs due to resistance, which converts electrical energy into heat as current flows through the circuit.
What is the standard frequency of AC supply in India?
A 50 Hz
B 60 Hz
C 100 Hz
D 25 Hz
The standard frequency of AC supply in India is 50 Hz, meaning the current changes direction 50 times per second.