Magnetism and Matter

32 solved questions from Class 12 Physics, each with the full working. Tap any question to see the step-by-step solution.

• 1 What is the fundamental law or governing principle of 'Magnetism and Matter' in Class 12 Physics? medium MCQ Fundamental Physical Law
• 2 What is the SI unit and dimensional formula for the key physical quantity studied in 'Magnetism and Matter'? medium MCQ SI Units & Dimensional Analysis
• 3 How does the field or potential intensity vary with distance r in 'Magnetism and Matter'? medium MCQ Spatial Distance Dependence
• 4 What is the net flux or circulation integral through a closed surface in 'Magnetism and Matter'? medium MCQ Gauss's Theorem & Boundary Integrals
• 5 Why do field lines in 'Magnetism and Matter' never intersect each other? medium MCQ Field Line Properties
• 6 A paramagnetic sample of volume 10.0 cm^3 is placed in a uniform magnetic field of 0.5 T. The magnetization measured is 0.04 A/m. (a) Calculate the magnetic susceptibility χ of the sample. (b) Explain whether the sample is paramagnetic or diamagnetic based on the sign of χ. hard 5 marks Magnetic susceptibility of paramagnetic material
• 7 A circular loop of radius 0.1 m carries a current of 2 A. Calculate the magnetic field at its centre and state the direction of the field if the current flows clockwise. medium 3 marks Magnetic field of a circular current loop
• 8 Find the magnitude and direction of the magnetic field at a point located 0.2 m from an infinitely long straight wire carrying a current of 5 A flowing through it. Use the right-hand rule to determine the direction. easy 2 marks Biot‑Savart law for infinite wire
• 9 A long solenoid has 800 turns per meter and carries a current of I=1.5 A. What is the magnetic field inside the solenoid? medium 2 marks Magnetic field inside a solenoid
• 10 A proton (charge +e=1.6×10^-19 C) moves with speed v=2.0×10^6 m s^-1 perpendicular to a uniform magnetic field of magnitude B=0.80 T directed into the page. Find the magnitude of the magnetic force on the proton and state the direction of the force using the right‑hand rule. easy 1 mark Magnetic force on a moving charge
• 11 A cylindrical piece of paramagnetic material of volume V=12.0 cm^3 is placed in a uniform magnetic field B=0.60 T. The measured magnetization is M=0.036 A m^-1. (a) Calculate the magnetic susceptibility χ of the material. (b) State whether the material is paramagnetic or diamagnetic based on the sign of χ. medium 2 marks Magnetic susceptibility and magnetization
• 12 A circular loop of radius R=5.0 cm carries a steady current I=3.0 A. (a) Derive the expression for the magnetic field on the axis of the loop at a distance x from its centre. (b) Using the derived formula, calculate the field at a point x=10 cm on the axis. State the direction of the field if the current is anticlockwise when viewed from the positive x‑axis. hard 3 marks Magnetic field on axis of a current loop
• 13 A solenoid has a density of 1000 turns per meter and carries a current of 2 A. What is the magnetic field inside the solenoid? easy 1 mark Magnetic field inside solenoid
• 14 A straight wire carrying a current of 10 A produces a magnetic field at a point 5.0 cm away from the wire. The value of the field is medium MCQ 3 marks Biot–Savart law for straight wire
• 15 An electron with speed 4.0×10^5;m s^-1 moves perpendicular to a uniform magnetic field of magnitude 0.30;T directed towards the observer. Find the magnitude and direction of the magnetic force on the electron. easy 2 marks Force on moving charge in magnetic field
• 16 A solenoid has 500 turns, length 0.20 m, radius 0.05 m, and carries a current of 3.0 A. It is placed in a uniform magnetic field of 0.10 T that is perpendicular to the axis of the solenoid. hard 5 marks Torque on magnetic dipole in external field
• 17 A rectangular current loop of width 4.0 cm and height 6.0 cm carries a current of 2.0 A. The loop is placed in a uniform magnetic field of magnitude 0.50 T that makes an angle of 60° with the normal to the plane of the loop. Calculate (i) the torque on the loop and (ii) the magnetic potential energy. State the direction of the torque relative to the field. hard 4 marks Torque on magnetic dipole
• 18 An electron (q=-e, e=1.60×10^-19,C) moves with a speed of 5.0×10^5,m,s^-1 perpendicular to a uniform magnetic field of magnitude 0.40,T directed along the +y–axis. Find the magnitude and direction of the magnetic force on the electron. medium 3 marks Magnetic force on moving charge
• 19 A straight wire carries a current of 4.0 A and a point 8.0 cm from the wire lies in its perpendicular bisector. What is the magnitude of the magnetic field at that point? easy 2 marks Magnetic field of straight wire
• 20 A ferrite sample of volume V=1.5×10^-5,m^3 is placed in a uniform magnetic field of B=0.80,T. The measured magnetization of the sample is M=4.5×10^-2,A,m^-1. (i) Calculate the magnetic susceptibility χ of the sample. (ii) Is the sample paramagnetic or diamagnetic? (iii) Find the magnetic moment of the sample. hard 5 marks Magnetic susceptibility of ferrite
• 21 A magnetic dipole moment μ=3.0;A,m^2 is placed in a uniform magnetic field of magnitude 0.4,T. If the dipole moment is perpendicular to the field, what is the torque experienced by the dipole? easy 2 marks torque on a magnetic dipole
• 22 A rectangular loop of width 10 cm and height 20 cm carries a current of 4 A. It is placed in a uniform magnetic field of 0.5 T that makes an angle of 30° with the normal to the loop. Find (i) the torque on the loop, (ii) the potential energy, and state the direction of the torque with respect to the field. hard 5 marks torque and potential energy of a current loop
• 23 An infinitely long straight wire carries a current of 6.0 A. Calculate the magnitude of the magnetic field at a point located 15 cm from the wire. State the direction of the field using the right‑hand rule. easy 1 mark Magnetic field of a straight current‑carrying wire
• 24 A rectangular loop of width 8 cm and height 12 cm carries a current of 3.0 A. The loop is placed in a uniform magnetic field of magnitude 0.60 T that makes an angle of 45° with the normal to the plane of the loop. Calculate the torque on the loop and state the direction in which the torque tends to rotate the loop. medium 2 marks Torque on a current loop in a magnetic field
• 25 A cylindrical paramagnetic sample has radius 2.0 cm and length 5.0 cm. It is placed in a uniform magnetic field of B=0.75 T. The measured magnetization of the sample is M=5.4×10^-2 A·m^-1.\n(a) Calculate the magnetic susceptibility χ of the material.\n(b) State whether the material is paramagnetic or diamagnetic.\n(c) Find the total magnetic moment μ of the sample. hard 4 marks Magnetization, susceptibility and magnetic moment of matter
• 26 A rectangular current loop of width 10,cm and height 15,cm carries a current of 4,A. It is placed in a uniform magnetic field of magnitude 0.50,T that makes an angle of 30° with the normal to the plane of the loop. (i) Calculate the torque on the loop. (ii) Calculate the magnetic potential energy of the loop. State the direction of the torque relative to the field. medium 3 marks Torque on current loop
• 27 A cylindrical paramagnetic sample has radius 2.0,cm and length 5.0,cm. It is placed in a uniform magnetic field of B=0.75,T. The measured magnetization of the sample is M=5.4×10^-2,A,m^-1. (a) Calculate the magnetic susceptibility χ of the material. (b) State whether the material is paramagnetic or diamagnetic. (c) Find the total magnetic moment μ of the sample. hard 4 marks Magnetic susceptibility
• 28 A proton with charge +e=1.6×10^-19,C moves at a speed of 4.0×10^5,m,s^-1 perpendicular to a uniform magnetic field of magnitude 0.30,T directed towards the observer (along the +z–axis). Calculate the magnitude and direction of the magnetic force on the proton. easy 1 mark Magnetic force on moving charge
• 29 A long straight wire carries a current of 5,A. Find the magnetic field magnitude and direction at a point 0.20,m from the wire, where the current is directed upwards along the +z–axis. medium 2 marks Magnetic field of long wire
• 30 A long straight wire carrying a current of 2:A runs along the +z–axis. Using the right–hand rule, determine the magnitude and direction of the magnetic field at a point 0.1:m away from the wire along the +x axis. easy MCQ 2 marks Magnetic field of an infinite straight wire
• 31 A toroidal coil has a total of 2000 turns wound uniformly on a ring whose mean radius is 0.25 m. The coil carries a current of 3.0 A. Using Ampère's circuital law, calculate the magnitude of the magnetic field at a point on the central circle inside the toroid (i.e. at a radial distance of 0.25 m from the symmetry axis). easy 3 marks Ampere's law applied to a toroid
• 32 A certain paramagnetic salt has a magnetic susceptibility of χ_1 = 9.0 × 10^-3 at a temperature of 300 K. The salt obeys Curie's law. What is its susceptibility when the temperature is raised to 900 K? medium MCQ 3 marks Curie's law for paramagnetic susceptibility