A transformer is used to change voltage levels in an alternating current (AC) circuit. By using electromagnetic induction, it either steps up or steps down the voltage depending on the turns ratio of its coils.
Which safety device is used to prevent electrical shocks?
A Fuse
B Ammeter
C GFCI
D Circuit breaker
A Ground Fault Circuit Interrupter (GFCI) is designed to protect people from electrical shocks. It detects differences between the hot and neutral wires and quickly shuts off power if an imbalance occurs, indicating a potential shock hazard.
What does the symbol of a resistor look like in an electrical diagram?
A Zig-zag line
B Circle
C Square
D Straight line
The resistor in an electrical diagram is represented by a zig-zag line, which indicates a component that resists the flow of current and converts electrical energy into heat.
What is the typical use of a capacitor in an electrical circuit?
A Measure voltage
B Control current
C Regulate temperature
D Store charge
A capacitor stores electrical charge in an electric field and can release the stored energy when needed. It is used in circuits for filtering, energy storage, and to smooth out voltage fluctuations.
What happens when more resistors are added in series?
A Voltage increases
B Current decreases
C Total resistance increases
D Total resistance decreases
In a series circuit, the total resistance increases as more resistors are added. The total resistance is the sum of the individual resistances, which makes it harder for the current to flow through the circuit.
What is the main characteristic of an ohmic conductor?
A Nonlinear current-voltage relationship
B Constant resistance
C Varying resistance
D Zero resistance
An ohmic conductor follows Ohm’s Law, meaning its resistance remains constant over a range of voltages and currents. Common examples include metals like copper, which have stable resistance at different voltages.
What device is used to measure the current flowing through a circuit?
A Ammeter
B Voltmeter
C Wattmeter
D Ohmmeter
An ammeter is used to measure the current flowing through a circuit. It is connected in series with the load, and its unit of measurement is amperes (A), representing the flow of electric charge.
What is the function of a circuit breaker?
A Control current
B Protect from overcurrent
C Increase resistance
D Measure voltage
A circuit breaker is designed to protect an electrical circuit from overcurrent conditions. It automatically disconnects the power when current exceeds a safe level, preventing damage to the circuit and minimizing the risk of electrical fires.
What happens to the total resistance in a parallel circuit as more resistors are added?
A Voltage increases
B Current decreases
C Total resistance increases
D Total resistance decreases
In a parallel circuit, adding more resistors decreases the total resistance. The current has more paths to flow through, making it easier for the current to flow, which reduces the overall resistance of the circuit.
Which of the following is a non-ohmic conductor?
A Silver
B Resistor
C Diode
D Copper
A diode is a non-ohmic conductor because it does not follow Ohm’s Law. Its resistance varies with the applied voltage, allowing current to flow in one direction and blocking it in the opposite direction.
What does the symbol of a battery look like in an electrical diagram?
A A rectangle
B Two long lines of unequal length
C A circle with a cross
D A series of short lines
A battery in an electrical diagram is represented by two long lines of unequal length, with the longer line representing the positive terminal and the shorter one representing the negative terminal. This symbol indicates a DC power source.
What is the unit of electrical power?
A Watt
B Ohm
C Ampere
D Volt
The unit of electrical power is the watt (W). It is the rate at which electrical energy is consumed or transferred in a circuit, and is calculated as the product of voltage (V) and current (I): P=VĂI.
Which type of current is most commonly used in household electrical wiring?
A Pulsating current
B Alternating current (AC)
C Reactive current
D Direct current (DC)
Alternating current (AC) is used in most household electrical wiring systems. AC changes direction periodically, which makes it easier to transmit over long distances and convert to different voltages using transformers.
What is the function of an inductor in a circuit?
A Store energy in a magnetic field
B Convert AC to DC
C Measure current
D Store charge
An inductor stores energy in the form of a magnetic field when current flows through it. Inductors resist changes in current and are used in filters, energy storage, and inductive heating applications.
What is the main effect of increasing the current through a conductor?
A Increases resistance
B Decreases temperature
C Reduces voltage
D Increases temperature
Increasing the current through a conductor results in more collisions between electrons and atoms, which increases the conductor’s temperature. This is known as Joule heating, and it can be used in devices like electric heaters.