Class 12 Physics MCQ Chapter 4 Moving Charges and Magnetism
Prepare smarter for your board examinations with our Class 12 Physics MCQ Chapter 4 Moving Charges and Magnetism English Medium collection. This article features a carefully curated set of multiple-choice questions (MCQs) with answers, designed to help AHSEC Higher Secondary students master one of the most important chapters in Physics.
The chapter Moving Charges and Magnetism explains the relationship between electricity and magnetism, covering key concepts such as magnetic fields, magnetic force on moving charges, Biot-Savart law, Ampere’s circuital law, force on a current-carrying conductor, torque on a current loop, cyclotron, and the motion of charged particles in magnetic fields. These topics play a crucial role in understanding electromagnetic phenomena and are frequently asked in board examinations.
All MCQs are based on the latest AHSEC syllabus and exam pattern, making them highly useful for revision and self-evaluation. Practicing these objective questions regularly will help students strengthen conceptual knowledge, improve problem-solving abilities, and become more confident in answering exam-oriented questions.
Whether you are revising important formulas or preparing for the AHSEC Higher Secondary Final Examination, these Chapter 4 MCQ solutions will help you identify key concepts and achieve better performance in Physics.
Part: I
Moving Charges and Magnetism
VSA & MCQ
I. Very Short Answer Questions
Q. What produces a magnetic field?
Ans: Moving charges or electric current produce a magnetic field.
Q. What is magnetic field?
Ans: A region around a magnet or current-carrying conductor where magnetic force is experienced.
Q. What is the SI unit of magnetic field?
Ans: Tesla (T).
Q. State Biot–Savart law.
Ans: dB = (μ₀ / 4π) × (I dl sinθ / r²).
Q. State Ampere’s circuital law.
Ans: ∮B · dl = μ₀I.
Q. What is Lorentz force?
Ans: Force on a charge q moving with velocity v in fields is F = q(E + v × B).
Q. What is magnetic force on a moving charge?
Ans: F = qvB sinθ.
Q. What is force on a current-carrying conductor?
Ans: F = BIL sinθ.
Q. What is the direction rule for magnetic force?
Ans: Fleming’s left-hand rule.
Q. What is the magnetic field due to a long straight wire?
Ans: B = (μ₀I) / (2πr).
Q. What is the field at the center of a circular loop?
Ans: B = (μ₀I) / (2R).
Q. What is solenoid?
Ans: A long coil of wire carrying current.
Q. What is magnetic field inside a solenoid?
Ans: B = μ₀nI.
Q. What is a toroid?
Ans: A circular solenoid.
Q. What is cyclotron?
Ans: A device to accelerate charged particles.
Q. What is cyclotron frequency?
Ans: f = (qB) / (2πm).
Q. What is radius of circular path in magnetic field?
Ans: r = mv / (qB).
Q. What is Hall effect?
Ans: Development of transverse voltage in a conductor in magnetic field.
Q. What is current density?
Ans: J = I / A.
Q. What is magnetic dipole moment of a loop?
Ans: m = IA.
Q. What is torque on a current loop?
Ans: τ = mB sinθ.
Q. What is moving coil galvanometer?
Ans: Device to detect small currents.
Q. What is sensitivity of galvanometer?
Ans: Deflection per unit current.
Q. What is conversion of galvanometer to ammeter?
Ans: By connecting low resistance in parallel.
Q. What is conversion to voltmeter?
Ans: By connecting high resistance in series.
Q. What is magnetic field direction around wire?
Ans: Given by right-hand thumb rule.
Q. What is permeability of free space?
Ans: μ₀ = 4π × 10⁻⁷ T·m/A.
Q. What is nature of magnetic field lines?
Ans: Closed continuous loops.
Q. What is force between parallel currents?
Ans: F/L = (μ₀I₁I₂) / (2πr).
Q. What happens to a charge moving parallel to B?
Ans: No force acts.
II. Multiple Choice Questions
Q. Magnetic field unit is:
(a) Tesla
(b) Volt
(c) Ohm
(d) Ampere
Ans: (a)
Q. Moving charges produce:
(a) Electric field only
(b) Magnetic field only
(c) Both
(d) None
Ans: (c)
Q. Force on charge is maximum when angle is:
(a) 0°
(b) 90°
(c) 180°
(d) 45°
Ans: (b)
Q. Cyclotron works on:
(a) Electric field
(b) Magnetic field
(c) Both
(d) Gravity
Ans: (c)
Q. Field inside solenoid is:
(a) Zero
(b) Uniform
(c) Infinite
(d) Random
Ans: (b)
Q. Magnetic field lines are:
(a) Open
(b) Closed
(c) Straight
(d) Parallel
Ans: (b)
Q. Ampere law relates:
(a) Current and field
(b) Voltage and current
(c) Power
(d) Resistance
Ans: (a)
Q. Lorentz force depends on:
(a) Charge
(b) Velocity
(c) Magnetic field
(d) All
Ans: (d)
Q. Parallel currents attract when:
(a) Same direction
(b) Opposite
(c) Zero
(d) Infinite
Ans: (a)
Q. Hall effect gives:
(a) Current
(b) Voltage
(c) Resistance
(d) Power
Ans: (b)
Q. Assertion: Magnetic field lines are closed. Reason: No monopoles exist.
(a) Both true, reason correct
(b) Both true, reason incorrect
(c) Assertion true, reason false
(d) Both false
Ans: (a)
Q. Assertion: Force is zero when v ∥ B. Reason: sin0° = 0.
(a) Both true, reason correct
(b) Both true, reason incorrect
(c) Assertion true, reason false
(d) Both false
Ans: (a)
Q. Assertion: Cyclotron cannot accelerate electrons at high speed. Reason: Mass changes.
(a) Both true, reason correct
(b) Both true, reason incorrect
(c) Assertion true, reason false
(d) Both false
Ans: (a)
Q. Assertion: Solenoid gives uniform field. Reason: Field lines are parallel inside.
(a) Both true, reason correct
(b) Both true, reason incorrect
(c) Assertion true, reason false
(d) Both false
Ans: (a)
Q. Assertion: Parallel currents attract. Reason: Magnetic interaction.
(a) Both true, reason correct
(b) Both true, reason incorrect
(c) Assertion true, reason false
(d) Both false
Ans: (a)
Q. Assertion: Torque acts on current loop. Reason: Magnetic dipole exists.
(a) Both true, reason correct
(b) Both true, reason incorrect
(c) Assertion true, reason false
(d) Both false
Ans: (a)
Q. Assertion: Hall voltage develops perpendicular. Reason: Charges deflect.
(a) Both true, reason correct
(b) Both true, reason incorrect
(c) Assertion true, reason false
(d) Both false
Ans: (a)
