Q.1 Which of the following particles experience a force in a magnetic field?
Proton
Neutron
Photon
Electron
Explanation - Charged particles, like protons and electrons, experience a force in a magnetic field. Neutrons and photons are uncharged.
Correct answer is: Proton
Q.2 The unit of magnetic flux is:
Tesla
Weber
Gauss
Ampere
Explanation - Magnetic flux is measured in Weber (Wb). Tesla measures magnetic field (B).
Correct answer is: Weber
Q.3 A current-carrying conductor placed in a magnetic field experiences a force. This is known as:
Lorentz Force
Electromagnetic Induction
Hall Effect
Faraday’s Law
Explanation - The force on a current-carrying conductor in a magnetic field is called the Lorentz force.
Correct answer is: Lorentz Force
Q.4 The magnetic field at the center of a circular loop carrying current I and radius R is:
μ₀I / 2πR
μ₀I / 2R
μ₀I / R²
μ₀I / 4πR²
Explanation - Magnetic field at the center of a circular current loop is given by B = μ₀I / 2R.
Correct answer is: μ₀I / 2R
Q.5 The phenomenon of producing emf due to relative motion between a magnet and a conductor is called:
Electromagnetic Induction
Hall Effect
Magnetic Susceptibility
Magnetic Hysteresis
Explanation - Faraday’s law of electromagnetic induction explains the generation of emf due to relative motion between a magnet and a conductor.
Correct answer is: Electromagnetic Induction
Q.6 Which law relates induced emf with the rate of change of magnetic flux?
Faraday’s Law
Lenz’s Law
Ampere’s Law
Gauss’s Law for Magnetism
Explanation - Faraday's law states that induced emf is equal to the negative rate of change of magnetic flux.
Correct answer is: Faraday’s Law
Q.7 The direction of induced current in a conductor is given by:
Lenz’s Law
Ampere’s Law
Biot-Savart Law
Gauss’s Law
Explanation - Lenz’s Law states that induced current flows in a direction to oppose the change causing it.
Correct answer is: Lenz’s Law
Q.8 The SI unit of magnetic field strength (H) is:
Tesla
Ampere/meter
Weber
Gauss
Explanation - Magnetic field strength H is measured in Ampere per meter (A/m). Tesla is for B, the magnetic flux density.
Correct answer is: Ampere/meter
Q.9 Magnetic field inside a long solenoid carrying current I and having n turns per unit length is:
μ₀nI
μ₀I / 2R
μ₀nI / 2
μ₀I / 2πR
Explanation - Magnetic field inside a long solenoid is B = μ₀ n I, uniform and along its axis.
Correct answer is: μ₀nI
Q.10 A material which gets magnetized in the direction of applied magnetic field and loses magnetism when removed is called:
Paramagnetic
Diamagnetic
Ferromagnetic
Antiferromagnetic
Explanation - Paramagnetic materials are weakly attracted by a magnetic field and do not retain magnetization after removal of field.
Correct answer is: Paramagnetic
Q.11 Magnetic lines of force never:
Form closed loops
Start from north pole
End at south pole
Cross each other
Explanation - Magnetic field lines never cross each other because at any point, magnetic field has a unique direction.
Correct answer is: Cross each other
Q.12 The torque experienced by a magnetic dipole of moment m in a uniform magnetic field B is:
m × B
m · B
m / B
B / m
Explanation - Torque τ on a magnetic dipole in a magnetic field is given by τ = m × B, perpendicular to both m and B.
Correct answer is: m × B
Q.13 Which of the following is a diamagnetic material?
Copper
Iron
Nickel
Cobalt
Explanation - Diamagnetic materials like copper are weakly repelled by a magnetic field and have no permanent magnetic moment.
Correct answer is: Copper
Q.14 The Hall effect is observed due to:
Lorentz force on moving charges
Magnetic field around a wire
Induced emf in a coil
Magnetic domains alignment
Explanation - Hall effect arises when a current-carrying conductor in a magnetic field develops a voltage across it due to Lorentz force on moving charges.
Correct answer is: Lorentz force on moving charges
Q.15 Magnetic susceptibility of a diamagnetic material is:
Positive
Negative
Zero
Infinite
Explanation - Diamagnetic materials have a small negative magnetic susceptibility and are repelled by magnetic fields.
Correct answer is: Negative
Q.16 The Biot-Savart law gives the magnetic field produced by:
A small segment of current
A magnetic dipole
A moving electron
A solenoid
Explanation - Biot-Savart law relates magnetic field at a point due to a small current element in space.
Correct answer is: A small segment of current
Q.17 The magnetic field at the center of a circular loop is directly proportional to:
Current in the loop
Square of radius
Number of turns squared
Resistance of the wire
Explanation - B at the center of a circular loop is directly proportional to the current I and inversely proportional to radius R.
Correct answer is: Current in the loop
Q.18 Earth’s magnetic field is approximately:
0.25 Gauss
0.5 Tesla
0.5 Gauss
1 Tesla
Explanation - Earth’s magnetic field is around 0.25 to 0.65 Gauss, very weak compared to laboratory magnets.
Correct answer is: 0.5 Gauss
Q.19 A solenoid behaves like a bar magnet when:
Current flows through it
It is heated
It is rotated
It is moved in space
Explanation - A solenoid produces a magnetic field along its axis when current passes through it, resembling a bar magnet.
Correct answer is: Current flows through it
Q.20 Which of the following is used to measure magnetic field strength?
Gaussmeter
Ammeter
Voltmeter
Tachometer
Explanation - Gaussmeter or magnetometer is used to measure magnetic field strength in Gauss or Tesla.
Correct answer is: Gaussmeter
Q.21 If a conductor moves parallel to a magnetic field, the induced emf is:
Maximum
Zero
Depends on length
Depends on resistance
Explanation - Emf is induced only if the conductor cuts magnetic lines of force. If motion is parallel to B, no flux is cut and emf is zero.
Correct answer is: Zero
Q.22 Magnetic flux is defined as:
B · A
B × A
B / A
B + A
Explanation - Magnetic flux Φ = B · A cosθ, the dot product of magnetic field and area vector.
Correct answer is: B · A
Q.23 The rate of change of magnetic flux through a loop induces an emf of 10 V. If flux changes from 0 to 0.05 Wb in 0.01 s, the induced emf is:
5 V
10 V
2 V
0 V
Explanation - Using Faraday’s law: emf = ΔΦ / Δt = 0.05 / 0.01 = 5 V.
Correct answer is: 5 V
Q.24 Which of the following increases the magnetic field inside a solenoid?
Increasing current
Increasing length
Decreasing number of turns
Removing the core
Explanation - B inside a solenoid is B = μ₀ n I. Increasing current I increases B linearly.
Correct answer is: Increasing current
Q.25 A bar magnet has poles at its ends. The magnetic field lines are:
From north to south outside
From south to north outside
Randomly oriented
Circular around the center
Explanation - Magnetic field lines emerge from north pole and enter the south pole outside the magnet.
Correct answer is: From north to south outside