The unit of electrical energy is the Joule (J). Energy is the ability to do work, and in electrical circuits, energy is the product of power (in watts) and time (in seconds). One joule is the energy expended when one watt of power is used for one second.
What type of current is supplied to homes?
A Direct current (DC)
B Both
C None
D Alternating current (AC)
Alternating current (AC) is supplied to homes. AC changes direction periodically, making it easier to transport over long distances. It is used in most household electrical appliances due to its efficiency and ease of generation.
What is the function of a resistor in a circuit?
A To increase voltage
B To limit current
C To store energy
D To measure power
A resistor limits the flow of electrical current in a circuit by providing resistance. The amount of resistance controls the current that passes through it. It is a fundamental component used in many circuits to prevent overloads.
Which unit is used to measure electrical conductance?
A Ohm
B Ampere
C Siemens
D Watt
Siemens (S) is the unit of electrical conductance, which measures how easily current can flow through a conductor. It is the reciprocal of resistance, where a higher conductance means easier flow of current.
What does an inductor store?
A Energy
B Current
C Voltage
D Charge
An inductor stores energy in the form of a magnetic field when current flows through it. It resists changes in current and is commonly used in filtering applications. The stored energy is proportional to the square of the current.
Which device measures voltage?
A Ammeter
B Ohmmeter
C Voltmeter
D Wattmeter
A voltmeter is used to measure the electrical potential difference, or voltage, between two points in a circuit. It is connected in parallel with the component whose voltage is to be measured, and it is calibrated in volts.
What is the function of a fuse?
A To prevent overload
B To increase current
C To store energy
D To change voltage
A fuse is a safety device designed to protect electrical circuits from overloads by breaking the circuit if the current exceeds a safe limit. It contains a wire that melts under excessive current, stopping further damage.
What is the unit of electrical resistance?
A Watt
B Ohm
C Volt
D Ampere
The unit of electrical resistance is the Ohm (Ω). It measures how much a material resists the flow of current. One ohm is the resistance that allows one ampere of current to flow when one volt is applied across it.
What does the term “electromagnetic induction” describe?
A Current flowing in a conductor
B Energy stored in a capacitor
C Energy conversion in transformers
D Voltage produced by a moving magnetic field
Electromagnetic induction is the process by which a changing magnetic field induces a voltage (or electromotive force) in a conductor. This principle is used in generators and transformers to convert mechanical energy into electrical energy.
What is the primary cause of energy loss in wires?
A Voltage drop
B Heat dissipation
C Magnetic fields
D Capacitance
The primary cause of energy loss in wires is heat dissipation, due to the resistance in the wire. As current flows through the conductor, energy is converted into heat. The higher the resistance, the more energy is lost as heat.
Which of these is a non-ohmic conductor?
A Copper wire
B Resistor
C Diode
D Aluminum wire
A diode is a non-ohmic conductor, meaning it does not follow Ohm’s Law. The current-voltage relationship is non-linear, and it only allows current to flow in one direction. This is useful in rectification circuits.
What type of circuit is used in household electrical wiring?
A Parallel
B Series
C Open
D Short
Household electrical wiring is typically arranged in parallel circuits. This allows each device to operate independently, so if one device fails, others continue to work. Voltage is the same across all devices in parallel.
What is the function of a transformer in an electrical circuit?
A To increase current
B To store energy
C To increase/decrease voltage
D To measure resistance
A transformer changes the voltage in an AC circuit by using electromagnetic induction. It can either increase or decrease the voltage, depending on the number of turns in the primary and secondary coils. This is crucial for power transmission.
What is the primary purpose of grounding in electrical systems?
A To measure voltage
B To protect from electric shock
C To store energy
D To increase resistance
Grounding provides a safe path for electric current to flow into the earth, protecting humans and equipment from electrical shocks. It helps to safely dissipate excess electricity and reduces the risk of electrical fires.
Which device is used to store electrical charge?
A Capacitor
B Battery
C Inductor
D Fuse
A capacitor stores electrical charge in an electric field between two conductive plates. The amount of charge stored is directly related to the voltage applied and the capacitance of the capacitor, and it is used in filtering and energy storage applications.