Introduction to Electrical Engineering MCQs (Part-8)
What is a conductor in electrical terms?
A Blocks current
B Allows current flow
C Opposes current flow
D Stores energy
A conductor is a material that allows electrical current to flow through it easily. Metals like copper and aluminum are good conductors because they have free electrons that facilitate the flow of electricity.
What is the primary function of an insulator?
A Allow current flow
B Increase current flow
C Store electrical energy
D Prevent current flow
An insulator is a material that resists the flow of electrical current. It prevents electricity from escaping or short-circuiting, ensuring safety by isolating conductors and protecting people from electrical shocks.
Which of the following is a semiconductor material?
A Iron
B Glass
C Silicon
D Copper
Silicon is a semiconductor material used in electronic devices like transistors, diodes, and solar cells. It has conductivity between conductors and insulators, which makes it suitable for controlling electrical current in circuits.
What is the role of a semiconductor in electronic devices?
A Block current
B Control current flow
C Increase current
D Store electrical energy
Semiconductors are used in electronic devices to control the flow of current. By adding impurities, their electrical properties can be altered to make them conduct or insulate, which is essential for components like transistors and diodes.
What happens to current in a conductor when voltage is applied?
A Stops
B Decreases
C Increases
D Remains constant
When voltage is applied to a conductor, it creates an electric field that pushes electrons, causing current to flow. The amount of current depends on the voltage and the conductor’s resistance, as per Ohm’s Law.
Which of the following materials is an example of an insulator?
A Plastic
B Steel
C Aluminum
D Copper
Plastic is an insulator that resists the flow of electrical current. It is commonly used to coat electrical wires and components to prevent electrical shock and short circuits by isolating conductive parts.
Which material is most commonly used as a conductor in electrical wiring?
A Wood
B Rubber
C Copper
D Glass
Copper is widely used for electrical wiring due to its high electrical conductivity. It allows for efficient current flow, making it an ideal material for power transmission and electrical circuits.
What is the key difference between a conductor and an insulator?
A Insulators allow current flow
B Conductors allow current flow
C Conductors store energy
D Insulators increase current
The key difference between conductors and insulators is that conductors allow electrical current to flow freely through them, while insulators resist the flow of electricity, preventing accidental electric shocks or short circuits.
What happens to a semiconductor’s conductivity when heated?
A Increases
B Stops
C Decreases
D Stays the same
In semiconductors, the conductivity increases with temperature. As temperature rises, more electrons gain enough energy to jump into the conduction band, allowing more current to flow through the material.
What is the primary use of semiconductors in electronics?
A To generate power
B To store electricity
C To regulate current
D To increase voltage
Semiconductors are used in electronic components like diodes and transistors to regulate the flow of current. By adjusting their conductivity, semiconductors help control electrical signals in devices such as computers and radios.
Which of these materials is commonly used as a conductor for power transmission?
A Glass
B Copper
C Wood
D Iron
Copper is the most common material used for power transmission lines due to its excellent electrical conductivity. It allows electricity to travel efficiently over long distances with minimal energy loss.
What defines the conductivity of a material?
A The amount of energy used
B Its resistance to current
C The number of free electrons
D Its ability to store charge
The conductivity of a material depends on the number of free electrons that can move through it. Materials with more free electrons, like metals, are good conductors, while insulators have very few free electrons.
What type of material is used to make electrical components that control current flow?
A Conductors
B Insulators
C Dielectrics
D Semiconductors
Semiconductors are used to make components like diodes and transistors that control the flow of electrical current. Their conductivity can be modified by adding impurities, making them essential for controlling electrical circuits.
What happens to the electrical resistance in a conductor if its length is doubled?
A Doubles
B Quadruples
C Stays the same
D Halves
Electrical resistance in a conductor is directly proportional to its length. If the length of the conductor is doubled, the resistance also doubles, as the current encounters more resistance as it travels through a longer material.
What is the primary reason that copper is used for wiring?
A Low resistance
B High temperature tolerance
C Low cost
D High conductivity
Copper is used for wiring primarily due to its high conductivity, which allows electricity to flow easily with minimal energy loss. It is also flexible and resistant to corrosion, making it ideal for electrical applications.