Introduction to Electrical Engineering MCQs (Part-9)
What is the SI unit of electric charge?
A Volt
B Ampere
C Coulomb
D Ohm
The SI unit of electric charge is the Coulomb (C). One Coulomb is the amount of charge transported by a current of one ampere in one second. It is a fundamental unit in electromagnetism.
What is the primary function of a magnetic field?
A Influence charged particles
B Increase resistance
C Store electric energy
D Block electric charge
A magnetic field exerts a force on moving charged particles. This is essential in applications like motors and transformers, where the movement of charges is controlled by magnetic fields to produce mechanical work.
What creates a magnetic field around a conductor?
A Capacitance
B Current
C Voltage
D Resistance
A magnetic field is generated around a conductor when current flows through it. This phenomenon is explained by Ampère’s Law, where the magnetic field’s strength depends on the current and the distance from the conductor.
What is the relationship between electricity and magnetism?
A Magnetism causes current flow
B Unrelated
C Voltage causes magnetism
D Electricity generates magnetism
Electric current generates a magnetic field around a conductor. This relationship is the basis of electromagnetism, which is utilized in devices like motors, transformers, and electromagnets, where electricity and magnetism work together.
Which of the following materials is magnetic?
A Rubber
B Aluminum
C Iron
D Copper
Iron is a ferromagnetic material, meaning it is strongly attracted to magnets and can be magnetized itself. This property is why iron is commonly used in the cores of electromagnets and transformers.
What does the term “electric flux” refer to?
A Flow of charge through a conductor
B The quantity of electric field passing through an area
C Resistance in an electric field
D Energy stored in a conductor
Electric flux refers to the total amount of electric field passing through a given area. It is directly proportional to the electric field strength and the area through which the field lines pass, and is measured in volt-meters (Vm).
What is the unit of magnetic flux?
A Weber
B Ampere
C Tesla
D Volt
The unit of magnetic flux is the Weber (Wb). It measures the total magnetic field passing through a given area. One Weber corresponds to one Tesla of magnetic flux passing through a square meter.
What happens when a charged particle moves through a magnetic field?
A It loses energy
B It accelerates
C It is deflected
D It becomes neutral
When a charged particle moves through a magnetic field, it experiences a force perpendicular to both its velocity and the magnetic field, causing it to follow a curved path. This is known as the Lorentz force.
Which of these is an example of an electrostatic phenomenon?
A Electric current
B Electromagnetic induction
C Magnetic force
D Electric charge interaction
Electrostatic phenomena involve stationary electric charges. When charges interact, they create electric fields and forces that can attract or repel each other. This is the basis for many effects in circuits and electrical devices.
What is the SI unit of magnetic field strength?
A Henry
B Tesla
C Weber
D Volt
The magnetic field strength is measured in Teslas (T). One Tesla is the magnetic field strength that will induce one volt of electromotive force in a conductor moving at one meter per second perpendicular to the field.
What happens when a conductor is placed in a magnetic field with current flowing through it?
A The magnetic field collapses
B The conductor heats up
C A force is exerted on the conductor
D The conductor resists movement
When a conductor carrying current is placed in a magnetic field, the magnetic force exerts a mechanical force on the conductor. This principle is the basis for how electric motors work, converting electrical energy into mechanical motion.
What is the effect of an electric field on a charged particle?
A It accelerates the particle
B It decelerates the particle
C It changes the mass
D It increases the charge
An electric field exerts a force on a charged particle, causing it to accelerate. The direction of acceleration depends on the sign of the charge and the direction of the electric field. Positive charges move in the field’s direction, and negative charges move in the opposite direction.
Which of the following is NOT a source of electric field?
A Electromagnetic wave
B Magnetic field
C Stationary charge
D Moving charge
Magnetic fields do not directly create electric fields. However, moving electric charges or varying magnetic fields can create electric fields (as described by Faraday’s Law of Induction), but a static magnetic field itself does not.
What is an example of a material that can be magnetized?
A Rubber
B Copper
C Wood
D Iron
Iron is a ferromagnetic material, meaning it can be magnetized. When exposed to a magnetic field, iron atoms align, creating a magnetic field within the material. This is why iron is often used in magnets and electromagnets.
What causes the deflection of a charged particle in a magnetic field?
A Magnetic force
B Electric force
C Lorentz force
D Gravitational force
The deflection of a charged particle in a magnetic field is caused by the Lorentz force, which is the combination of electric and magnetic forces acting on the particle. This force causes the particle to follow a curved trajectory.