The SI unit of electric current is the ampere (A). It represents the flow of electric charge per second. One ampere is equal to one coulomb of charge passing through a conductor in one second.
Which law states that the current through a conductor is directly proportional to the voltage across it, provided the temperature remains constant?
A Kirchhoff’s Voltage Law
B Ohm’s Law
C Faraday’s Law
D Joule’s Law
Ohm’s Law states \( V = IR \), where \( V \) is voltage, \( I \) is current, and \( R \) is resistance. This relationship holds true as long as the conductor’s temperature remains constant.
What type of circuit allows electric current to flow along multiple paths?
A Series Circuit
B Parallel Circuit
C Open Circuit
D Short Circuit
In a parallel circuit, current can flow through multiple branches. Each branch operates independently, and the voltage across each branch is the same.
Which device is used to measure electric current in a circuit?
A Voltmeter
B Ammeter
C Wattmeter
D Ohmmeter
An ammeter is connected in series with the circuit to measure the flow of current. It has low internal resistance to minimize voltage drop.
What is the function of a fuse in an electrical circuit?
A To increase voltage
B To protect the circuit from overload
C To store energy
D To reduce resistance
A fuse contains a wire that melts when the current exceeds a specified limit, interrupting the circuit and preventing damage from overheating or fire.
In a DC circuit, the power is calculated as:
A \( P = IV \)
B \( P = I^2R \)
C \( P = V^2/R \)
D None of the above
In a DC circuit, power can be calculated using \( P = IV \), \( P = I^2R \), or \( P = V^2/R \), depending on the known quantities.
Which material is commonly used as a conductor in electrical wiring?
A Copper
B Rubber
C Glass
D Wood
Copper is widely used in electrical wiring due to its high electrical conductivity, ductility, and resistance to corrosion.
What happens to the total resistance in a series circuit when more resistors are added?
A It decreases
B It increases
C It remains the same
D It becomes zero
In a series circuit, resistances are added directly: \( R_{\text{total}} = R_1 + R_2 + R_3 + \ldots \). Adding more resistors increases the total resistance.
What is the primary purpose of a transformer?
A To generate electricity
B To measure current
C To change the voltage level
D To store energy
A transformer transfers electrical energy between two circuits using electromagnetic induction and can step up or step down voltage levels.
Which of the following quantities remains constant in a series circuit?
A Current
B Voltage
C Resistance
D Power
In a series circuit, the same current flows through all components since there is only one path for the current.
What does the term “electrical grounding” refer to?
A Reducing voltage
B Connecting a circuit to the Earth
C Increasing current flow
D Stopping electric shocks
Grounding provides a safe path for excess current to flow into the Earth, protecting people and equipment from electric shocks.
Which law governs the total voltage around a closed loop in a circuit?
A Kirchhoff’s Voltage Law
B Ohm’s Law
C Coulomb’s Law
D Ampere’s Law
Kirchhoff’s Voltage Law states that the sum of all voltages around a closed loop is zero, accounting for voltage rises and drops.
What is the main reason for using insulation on electrical wires?
A To reduce voltage
B To prevent current flow
C To avoid electric shocks
D To improve conductivity
Insulation covers the conductor to prevent accidental contact, reducing the risk of electric shocks and short circuits.
What is the primary function of a capacitor in an AC circuit?
A To store charge
B To increase resistance
C To decrease voltage
D To block DC current
A capacitor allows AC signals to pass while blocking DC due to its impedance. It also stores charge temporarily.
The resistance of a conductor depends on:
A Length and material
B Cross-sectional area
C Temperature
D All of the above
Resistance depends on a conductor’s length, cross-sectional area, material resistivity, and temperature.
What is the unit of electrical energy?
A Joule
B Watt
C Volt
D Ampere
Electrical energy is measured in joules (J). One joule is the energy transferred when one watt of power is used for one second.
Which of the following is a non-ohmic conductor?
A Copper wire
B Filament of a bulb
C Aluminum wire
D Gold wire
Non-ohmic conductors do not follow Ohm’s Law. The resistance of a bulb filament changes with temperature, making it non-ohmic.
What is the function of a diode?
A To amplify current
B To allow current in one direction only
C To store electrical energy
D To reduce resistance
A diode is a semiconductor device that permits current flow in one direction and blocks it in the opposite direction.
Which of the following is a passive electrical component?
A Transistor
B Resistor
C Thyristor
D Diode
A passive component, like a resistor, does not generate power but dissipates or stores it.
What does an electric circuit require to work?
A A power source
B Conductors
C A load
D All of the above
An electric circuit must include a power source (e.g., battery), conductors (e.g., wires), and a load (e.g., bulb) to function properly.