Magnetism & EMI
Q. What is the phenomenon called when a changing magnetic field induces an electric current in a conductor?
A.
Electromagnetic induction
B.
Electrolysis
C.
Magnetic resonance
D.
Thermal conduction
Show solution
Solution
The phenomenon of inducing an electric current in a conductor due to a changing magnetic field is known as electromagnetic induction.
Correct Answer: A — Electromagnetic induction
Learn More →
Q. What is the phenomenon called when a changing magnetic field induces an electromotive force (EMF) in a circuit?
A.
Electromagnetic induction
B.
Magnetic resonance
C.
Electrolysis
D.
Magnetization
Show solution
Solution
The phenomenon is known as electromagnetic induction, as described by Faraday's law.
Correct Answer: A — Electromagnetic induction
Learn More →
Q. What is the phenomenon called when a changing magnetic field induces an electromotive force (EMF) in a conductor?
A.
Electromagnetic induction
B.
Magnetic resonance
C.
Electrolysis
D.
Magnetization
Show solution
Solution
The phenomenon of inducing an EMF in a conductor due to a changing magnetic field is known as electromagnetic induction.
Correct Answer: A — Electromagnetic induction
Learn More →
Q. What is the phenomenon called when a conductor moves through a magnetic field and generates an electric current?
A.
Electromagnetic induction
B.
Magnetic hysteresis
C.
Electrostatic induction
D.
Magnetic flux
Show solution
Solution
This phenomenon is known as electromagnetic induction, where a changing magnetic field induces an electric current in a conductor.
Correct Answer: A — Electromagnetic induction
Learn More →
Q. What is the phenomenon of electromagnetic induction?
A.
The generation of electric current by a changing magnetic field
B.
The generation of magnetic field by a changing electric current
C.
The interaction between electric and magnetic fields
D.
The conversion of mechanical energy into electrical energy
Show solution
Solution
Electromagnetic induction refers to the generation of electric current in a conductor due to a changing magnetic field.
Correct Answer: A — The generation of electric current by a changing magnetic field
Learn More →
Q. What is the power factor in a circuit with a phase angle of 60 degrees?
A.
0.5
B.
0.866
C.
1
D.
0
Show solution
Solution
The power factor is cos(60°) = 0.5.
Correct Answer: B — 0.866
Learn More →
Q. What is the power factor of a circuit with a phase angle of 60 degrees?
A.
0.5
B.
0.866
C.
1
D.
0.707
Show solution
Solution
The power factor (PF) is given by cos(θ). For a phase angle of 60 degrees, PF = cos(60°) = 0.5.
Correct Answer: B — 0.866
Learn More →
Q. What is the power factor of an AC circuit with a phase angle of 60 degrees?
A.
0.5
B.
0.866
C.
1
D.
0.707
Show solution
Solution
The power factor (PF) is given by cos(θ). For a phase angle of 60 degrees, PF = cos(60°) = 0.5.
Correct Answer: B — 0.866
Learn More →
Q. What is the primary reason for the operation of an electric motor?
A.
Electromagnetic induction
B.
Lorentz force
C.
Coulomb's law
D.
Ohm's law
Show solution
Solution
Electric motors operate based on the Lorentz force, which acts on current-carrying conductors in a magnetic field, causing rotation.
Correct Answer: B — Lorentz force
Learn More →
Q. What is the principle behind electromagnetic induction?
A.
Magnetic fields can create electric fields
B.
Electric fields can create magnetic fields
C.
Both A and B
D.
None of the above
Show solution
Solution
Electromagnetic induction is based on the principle that a changing magnetic field can induce an electric field and vice versa.
Correct Answer: C — Both A and B
Learn More →
Q. What is the principle behind the operation of an electric generator?
A.
Electromagnetic induction
B.
Thermal expansion
C.
Photoelectric effect
D.
Chemical reaction
Show solution
Solution
Electric generators operate on the principle of electromagnetic induction, converting mechanical energy into electrical energy.
Correct Answer: A — Electromagnetic induction
Learn More →
Q. What is the principle behind the operation of an electric motor?
A.
Electromagnetic induction
B.
Lorentz force
C.
Magnetic resonance
D.
Thermal expansion
Show solution
Solution
Electric motors operate on the principle of the Lorentz force, where a current-carrying conductor in a magnetic field experiences a force that causes it to rotate.
Correct Answer: B — Lorentz force
Learn More →
Q. What is the principle behind the working of an electric generator?
A.
Electromagnetic induction
B.
Electrolysis
C.
Thermal expansion
D.
Photoelectric effect
Show solution
Solution
An electric generator works on the principle of electromagnetic induction, where mechanical energy is converted into electrical energy by moving a conductor through a magnetic field.
Correct Answer: A — Electromagnetic induction
Learn More →
Q. What is the principle behind the working of an electric motor?
A.
Electromagnetic induction
B.
Lorentz force
C.
Magnetic resonance
D.
Electrolysis
Show solution
Solution
An electric motor operates on the principle of the Lorentz force, which states that a current-carrying conductor in a magnetic field experiences a force.
Correct Answer: B — Lorentz force
Learn More →
Q. What is the relationship between current and magnetic field in a long straight conductor?
A.
Directly proportional
B.
Inversely proportional
C.
Independent
D.
Exponential
Show solution
Solution
The magnetic field around a long straight conductor is directly proportional to the current flowing through it.
Correct Answer: A — Directly proportional
Learn More →
Q. What is the relationship between the magnetic field and the distance from a long straight wire carrying current?
A.
Directly proportional
B.
Inversely proportional
C.
Independent
D.
Exponential
Show solution
Solution
The magnetic field around a long straight wire is inversely proportional to the distance from the wire, as given by B = μ₀I/2πr.
Correct Answer: B — Inversely proportional
Learn More →
Q. What is the relationship between the magnetic field and the enclosed current according to Ampere's Law?
A.
B is proportional to the square of the current
B.
B is inversely proportional to the current
C.
B is directly proportional to the current
D.
B is independent of the current
Show solution
Solution
According to Ampere's Law, the magnetic field B is directly proportional to the enclosed current.
Correct Answer: C — B is directly proportional to the current
Learn More →
Q. What is the right-hand rule used for in magnetism?
A.
To determine the direction of current
B.
To find the direction of magnetic field
C.
To find the direction of force on a charge
D.
All of the above
Show solution
Solution
The right-hand rule helps determine the direction of current, magnetic field, and force on a charge in magnetic fields.
Correct Answer: D — All of the above
Learn More →
Q. What is the RMS value of an AC voltage given by V(t) = V0 sin(ωt)?
A.
V0
B.
V0/√2
C.
V0√2
D.
0
Show solution
Solution
The RMS value of an AC voltage is given by V_rms = V0/√2.
Correct Answer: B — V0/√2
Learn More →
Q. What is the role of a commutator in a DC motor?
A.
To convert AC to DC
B.
To reverse the direction of current
C.
To increase voltage
D.
To decrease resistance
Show solution
Solution
The commutator in a DC motor reverses the direction of current in the coil every half turn, ensuring continuous rotation in one direction.
Correct Answer: B — To reverse the direction of current
Learn More →
Q. What is the root mean square (RMS) value of an alternating current (AC) if its peak value is 10 A?
A.
5 A
B.
7.07 A
C.
10 A
D.
14.14 A
Show solution
Solution
The RMS value of an AC is given by I_rms = I_peak / √2. Therefore, I_rms = 10 A / √2 = 7.07 A.
Correct Answer: B — 7.07 A
Learn More →
Q. What is the root mean square (RMS) value of an alternating current (AC) that has a peak value of 10 A?
A.
5 A
B.
7.07 A
C.
10 A
D.
14.14 A
Show solution
Solution
The RMS value of an AC is given by I_rms = I_peak / √2. Therefore, I_rms = 10 A / √2 = 7.07 A.
Correct Answer: B — 7.07 A
Learn More →
Q. What is the shape of the magnetic field lines around a bar magnet?
A.
Straight lines
B.
Concentric circles
C.
Closed loops
D.
Random
Show solution
Solution
The magnetic field lines around a bar magnet form closed loops, exiting from the north pole and entering the south pole.
Correct Answer: C — Closed loops
Learn More →
Q. What is the shape of the magnetic field lines around a long straight conductor carrying current?
A.
Straight lines
B.
Concentric circles
C.
Ellipses
D.
Spirals
Show solution
Solution
The magnetic field lines around a long straight conductor are concentric circles centered on the wire.
Correct Answer: B — Concentric circles
Learn More →
Q. What is the total energy stored in an inductor with inductance L carrying a current I?
A.
LI^2
B.
0.5LI^2
C.
I^2/L
D.
0.5I^2/L
Show solution
Solution
The energy stored in an inductor is given by U = 0.5LI^2.
Correct Answer: B — 0.5LI^2
Learn More →
Q. What is the unit of impedance in an AC circuit?
A.
Ohm
B.
Farad
C.
Henry
D.
Coulomb
Show solution
Solution
The unit of impedance in an AC circuit is Ohm, which is the same as resistance.
Correct Answer: A — Ohm
Learn More →
Q. What is the unit of inductance?
A.
Ohm
B.
Henry
C.
Farad
D.
Coulomb
Show solution
Solution
The unit of inductance is Henry (H).
Correct Answer: B — Henry
Learn More →
Q. What is the unit of magnetic field strength (B)?
A.
Tesla
B.
Weber
C.
Henry
D.
Ampere
Show solution
Solution
The unit of magnetic field strength is Tesla (T).
Correct Answer: A — Tesla
Learn More →
Q. What is the unit of magnetic field strength as defined by the Biot-Savart Law?
A.
Tesla
B.
Newton
C.
Coulomb
D.
Ampere
Show solution
Solution
The unit of magnetic field strength is Tesla (T).
Correct Answer: A — Tesla
Learn More →
Q. What is the unit of magnetic field strength as derived from Biot-Savart Law?
A.
Tesla
B.
Ampere
C.
Weber
D.
Henry
Show solution
Solution
The unit of magnetic field strength is Tesla (T), which is derived from the Biot-Savart Law.
Correct Answer: A — Tesla
Learn More →
Showing 361 to 390 of 418 (14 Pages)