An electric fuse contains a thin wire that melts and breaks the circuit when the current exceeds a safe limit, preventing damage to devices and potential hazards.
Which law relates the voltage, current, and resistance in an electrical circuit?
A Kirchhoff’s Voltage Law
B Ohm’s Law
C Faraday’s Law
D Lenz’s Law
Ohm’s Law states that \( V = IR \), where \( V \) is voltage, \( I \) is current, and \( R \) is resistance.
What type of conductor does not obey Ohm’s Law?
A Ohmic conductor
B Non-ohmic conductor
C Ideal conductor
D Pure conductor
Non-ohmic conductors, such as diodes and transistors, do not have a linear relationship between voltage and current and therefore do not follow Ohm’s Law.
What does an electric motor convert?
A Electrical energy into thermal energy
B Mechanical energy into electrical energy
C Electrical energy into mechanical energy
D Chemical energy into electrical energy
Electric motors transform electrical energy into mechanical energy, enabling the operation of various machines and devices.
Which quantity remains constant in a parallel circuit?
A Current
B Resistance
C Voltage
D Power
In a parallel circuit, all components share the same voltage, as they are connected across the same potential difference.
What is the unit of electrical resistance?
A Ampere
B Coulomb
C Ohm
D Volt
Electrical resistance is measured in ohms (Ω), which quantifies how much a material opposes the flow of electric current.
What happens to the total resistance when resistors are connected in series?
A It increases
B It decreases
C It remains constant
D It becomes zero
In a series connection, the total resistance is the sum of all individual resistances: \( R_{\text{total}} = R_1 + R_2 + R_3 \).
Which of the following devices is used to measure electric current?
A Ammeter
B Voltmeter
C Ohmmeter
D Thermometer
An ammeter measures electric current and is connected in series with the circuit to ensure accurate current measurement.
Which type of transformer increases voltage?
A Step-down transformer
B Step-up transformer
C Isolation transformer
D Autotransformer
A step-up transformer increases the input voltage by using a higher number of turns in the secondary coil than in the primary coil.
What is the primary function of a rectifier?
A To increase resistance
B To convert DC to AC
C To convert AC to DC
D To step up voltage
A rectifier uses diodes to convert alternating current (AC) to direct current (DC), which is used in various electronic devices.
Which component is used to store charge in an electrical circuit?
A Resistor
B Inductor
C Capacitor
D Transformer
A capacitor stores electrical energy in the form of an electric field between its plates when a voltage is applied.
What is the effect of temperature on the resistance of a metallic conductor?
A Resistance increases with temperature
B Resistance decreases with temperature
C Resistance remains constant
D Resistance becomes zero
In metallic conductors, the resistance increases with temperature due to increased collisions between electrons and lattice ions.
What is the frequency of AC supply in the USA?
A 50 Hz
B 60 Hz
C 100 Hz
D 25 Hz
The standard frequency of AC supply in the USA is 60 Hz, meaning the current changes direction 60 times per second.
What is the primary cause of energy loss in a transformer?
A Copper loss
B Eddy current loss
C Hysteresis loss
D All of the above
Transformers experience energy loss due to copper loss (in winding resistance), eddy current loss (in the core), and hysteresis loss (due to magnetization).
What is the role of an Earth wire in a circuit?
A To carry the load current
B To protect against electric shock
C To increase voltage
D To measure resistance
An Earth wire provides a safe path for leakage current to flow into the ground, protecting users from electric shocks.
What type of energy is produced in a generator?
A Mechanical energy
B Chemical energy
C Electrical energy
D Thermal energy
A generator converts mechanical energy into electrical energy using electromagnetic induction.
What is the main factor that determines the capacitance of a capacitor?
A Resistance of the circuit
B Distance between plates
C Length of wire
D Frequency of the supply
The capacitance of a capacitor is directly proportional to the plate area and inversely proportional to the distance between the plates.
What happens when a conductor moves through a magnetic field?
A No effect
B Current is induced in the conductor
C Resistance increases
D Magnetic field decreases
When a conductor moves through a magnetic field, electromagnetic induction generates an EMF, which induces current in the conductor.
What is the purpose of insulation on electrical wires?
A To conduct electricity
B To prevent current leakage
C To increase voltage
D To reduce power loss
Insulation around electrical wires prevents accidental contact, leakage of current, and short circuits.
Which type of current flows in one direction only?
A Alternating Current (AC)
B Direct Current (DC)
C Pulsating Current
D Static Current
Direct Current (DC) flows steadily in one direction, making it suitable for batteries and electronic devices.
Which of the following devices is used to measure electric current?
A Ammeter
B Voltmeter
C Ohmmeter
D Thermometer
An ammeter measures electric current and is connected in series with the circuit to ensure accurate current measurement.