Q1. Which of the following is a fundamental property of a magnetic field?
a) Charge
b) Mass
c) Spin
d) Magnetization
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Correct Answer: c) Spin
Explanation: Spin is a fundamental property of particles, such as electrons, which gives rise to their intrinsic magnetic moment and contributes to the magnetic field. It determines the orientation of the magnetic dipole associated with the particle.
Q2. The phenomenon of electromagnetic induction was discovered by:
a) Michael Faraday
b) Isaac Newton
c) Albert Einstein
d) James Clerk Maxwell
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Correct Answer: a) Michael Faraday
Explanation: Michael Faraday discovered the phenomenon of electromagnetic induction in the early 19th century. He demonstrated that a changing magnetic field can induce an electromotive force (EMF) in a conductor, leading to the generation of electric currents.
Q3. Which of the following devices is based on the principle of electromagnetic induction?
a) Transformer
b) Capacitor
c) Diode
d) Resistor
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Correct Answer: a) Transformer
Explanation: A transformer is a device that operates on the principle of electromagnetic induction. It consists of two or more coils of wire (known as primary and secondary coils) that are magnetically coupled. Alternating current in the primary coil induces a changing magnetic field, which, in turn, induces a voltage in the secondary coil.
Q4. Ampere is a unit of measurement for:
a) Electric Charge
b) Electric Potential
c) Electric Current
d) Electric Resistance
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Correct Answer: c) Electric Current
Explanation: Ampere (A) is the SI unit of electric current. It measures the rate of flow of electric charge past a given point in a circuit. One ampere is defined as one coulomb of charge passing through a point in one second.
Q5. The force experienced by a charged particle moving in a magnetic field is given by:
a) Coulomb’s Law
b) Faraday’s Law
c) Ohm’s Law
d) Lorentz Force Law
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Correct Answer: d) Lorentz Force Law
Explanation: The force experienced by a charged particle moving in a magnetic field is given by the Lorentz Force Law. It states that the force (F) acting on a charged particle with charge q moving with velocity v in a magnetic field B is given by the equation F = qvBsinθ, where θ is the angle between v and B.
Q6. The direction of the magnetic field lines around a current-carrying wire can be determined using:
a) Fleming’s Right-Hand Rule
b) Fleming’s Left-Hand Rule
c) Lenz’s Law
d) Gauss’s Law
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Correct Answer: b) Fleming’s Left-Hand Rule
Explanation: Fleming’s Left-Hand Rule is used to determine the direction of the magnetic field lines around a current-carrying conductor. By pointing the thumb of the left hand in the direction of the current and aligning the index finger with the direction of the magnetic field, the middle finger indicates the direction of motion (or force) experienced by a positive charge.
Q7. Which of the following materials is commonly used as a core in electromagnets?
a) Copper
b) Aluminum
c) Iron
d) Silver
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Correct Answer: c) Iron
Explanation: Iron is commonly used as a core material in electromagnets due to its high magnetic permeability, which enhances the strength of the magnetic field produced by the coil. It allows for efficient concentration and transmission of magnetic flux.
Q8. Which law states that the induced electromotive force (emf) in a closed circuit is directly proportional to the rate of change of magnetic flux through the circuit?
a) Ohm’s Law
b) Faraday’s Law
c) Coulomb’s Law
d) Gauss’s Law
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Correct Answer: b) Faraday’s Law
Explanation: Faraday’s Law of electromagnetic induction states that the induced electromotive force (emf) in a closed circuit is directly proportional to the rate of change of magnetic flux through the circuit. It is mathematically represented as ∆Φ = -N∆(B.A)/∆t, where ∆Φ is the change in magnetic flux, N is the number of turns in the coil, B is the magnetic field, A is the area, and ∆t is the change in time.
Q9. Which of the following statements about magnetic fields is true?
a) Magnetic field lines only exist outside magnets.
b) Magnetic field lines always point from south to north.
c) Magnetic field lines do not intersect.
d) Magnetic field strength decreases with distance from the magnet.
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Correct Answer: c) Magnetic field lines do not intersect.
Explanation: Magnetic field lines do not intersect each other. If they were to intersect, it would imply that a magnetic field would exert a force in two different directions at the same point, which is not possible. The absence of intersections ensures the uniqueness of the direction of the magnetic field at any given point.
Q10. Which of the following equations represents Ampere’s law, a fundamental relationship in electromagnetism?
a) ∮ B ⋅ dl = μ₀I
b) ∮ E ⋅ dA = ε₀Q
c) ∮ B ⋅ dA = μ₀ε₀∂Φ/∂t
d) ∮ E ⋅ dl = -∂Φ/∂t
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Correct Answer: a) ∮ B ⋅ dl = μ₀I
Explanation: Ampere’s law states that the line integral of the magnetic field B around a closed loop is equal to the permeability of free space (μ₀) multiplied by the total current passing through the surface enclosed by the loop. Mathematically, it is represented as ∮ B ⋅ dl = μ₀I, where μ₀ is the permeability of free space and I is the total current passing through the loop.