Magnetism & Matter PYQs Set 1 (PDF)

Set 1 of 6 · Questions 1-30 of 164

In the print window choose “Save as PDF”. The file prints without a web address or date line.

Mere Teacher · Previous Year Questions NEET Physics · Magnetism & Matter · Set 1 (Q1-30)
Scan or visit mereteacher.com for free PYQ practice, timed CBT tests, step-by-step solutions and BroBot AI. Answers and solutions are free with a sign-up.
1. $The magnetic susceptibility of a material of a rod is 499. Permeability in vacuum is 4 π \times 1 0^{- 7} H / m . Absolute permeability of the material of the rod is:$ (1) $4π\times 1 0^{- 4} H/m$ (2) $2π\times 1 0^{- 4} H/m$ (3) $3π\times 1 0^{- 4} H/m$ (4) $π \times 1 0^{- 4} H / m$ 2. $A paramagnetic sample shows a net magnetization of 8 A m^{- 1} when placed in an external magnetic field of 0.6 T at a temperature of 4 K . When the same sample is placed in an external magnetic field of 0.2 T at a temperature of 16 K . The magnetization will be$ (1) $6 Am^{- 1}$ (2) $2.4 A m^{- 1}$ (3) $\frac{32}{3} A m^{- 1}$ (4) $\frac{2}{3} Am^{- 1}$ 3. $A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It$ (1) $will become rigid showing no movement$ (2) $will stay in any position$ (3) $will stay in north‐south direction only$ (4) $will stay in east‐west direction only$ 4. $The Curie temperature T_{C} represents$ (1) $temperature of transition from paramagnetic to ferromagnetic$ (2) $temperature of transition from paramagnetic to diamagnetic$ (3) $temperature of transition from ferromagnetic to paramagnetic$ (4) $temperature of transition from diamagnetic to paramagnetic$ 5. $A bar magnet is hung by a thin cotton thread in a uniform horizontal magnetic field and is in equilibrium state. The energy required to rotate it by 6 0^{o} is W . Now the torque required to keep the magnet in this new position is$ (1) $\frac{W}{3}$ (2) $3 W$ (3) $\frac{3 W}{2}$ (4) $\frac{2 W}{3}$ 6. $A solid metal cube of edge length 2 cm is moving in a positive y -direction at a constant speed of 6 m/s. There is a uniform magnetic field of 0.1 T in the positive z -direction. The potential difference between the two faces of the cube perpendicular to the x -axis, is:$ (1) $12 mV$ (2) $6 mV$ (3) $1 mV$ (4) $2 mV$ 7. $A bar magnet is demagnetized by inserting it inside a solenoid of length 0.2 m, 100 turns, and carrying a current of 5.2 A The coercivity of the bar magnet is:$ (1) $285 A / m$ (2) $2600 A / m$ (3) $520 A / m$ (4) $1200 A / m$ 8. $A magnetic dipole of magnetic moment 6 \times 10^{- 2} A m^{2} and moment of inertia 12 \times 10^{- 6} kg m^{2} performs oscillations in a magnetic field of 2 \times 10^{- 2} T . The time taken by the dipole to complete 20 oscillations is (π \approx 3)$ (1) $6 s$ (2) $12 s$ (3) $36 s$ (4) $18 s$ 9. $In the hysteresis curve the value of magnetization (B) which will be present in a substance when value of magnetizing force (H) is made zero (H = 0) is called as$ (1) $coercivity$ (2) $domain$ (3) $retentivity$ (4) $saturation$ 10. $A paramagnetic sample showing a net magnetisation of 0.8 Am^{- 1}, when placed in an external magnetic field of strength 0.8 T, at a temperature 5 K . If the temperature is raised to 20 K, then the magnetisation becomes$ (1) $0.8 A m^{- 1}$ (2) $0.2 A m^{- 1}$ (3) $0.1 A m^{- 1}$ (4) $0.4 A m^{- 1}$ 11. $What will be the nature of flow of water from a circular tap, when its flow rate increased from 0. \frac{18 L}{min} to 0. \frac{48 L}{min} ? The radius of the tap and viscosity of water are 0.5 cm and 10^{- 3} Pas, respectively.(Density of water : (: \frac{10 ^{3} kg}{m ^{3}})$ (1) $Unsteady to steady flow$ (2) $Remains steady flow$ (3) $Remains turbulent flow$ (4) $Steady flow to unsteady flow$ 12. $The period of oscillation of a bar magnet at a place is 2 s . At the same place, the period of oscillation of another identical bar magnet whose magnetic moment is 4 times to that of first magnet is$ (1) $4 s$ (2) $1 s$ (3) $2 s$ (4) $0.5 s$ 13. $Young’s modulus of two wires A and B are in the ratio 7 : 4. Wire A is 2 m long and has radius R. Wire A is 2 m long and has radius R. Wire B is 1.5 m long and has radius 2 mm. If the two wires stretch by the same length for a given load, then the value of R is close to:$ (1) $1.5 mm$ (2) $1.9 mm$ (3) $1.7 mm$ (4) $1.3 mm$ 14. $A particle is travelling 4 times as fast as an electron. Assuming the ratio of de-Broglie wavelength of a particleto that of electron is 2 : 1, the mass of the particle is:-$ (1) $116 times the mass of e^{-}$ (2) $8 times the mass of e^{-}$ (3) $16 times the mass of e^{-}$ (4) $\frac{1}{8} times the mass of e^{-}$ 15. $A compass needle oscillates 20 times per minute at a place where the dip is 45^{\circ} and the magnetic field is B_{1} . The same needle oscillates 30 times per minute at a place where the dip is 30^{\circ} and magnetic field is B_{2} . Then B_{1} : B_{2} is$ (1) $93 : 42$ (2) $42 : 93$ (3) $33 : 22$ (4) $22 : 33$ 16. $Two identical photocathodes receive the light of frequencies f_{1} and f_{2} respectively. If the velocities of the photo-electrons coming out are V_{1} and V_{2} respectively, then$ (1) $v_{1}^{2} - v_{2}^{2} = \frac{2 h}{m} (f_{1} - f_{2})$ (2) $v_{1}^{2} + v_{2}^{2} = \frac{2 h}{m} (f_{1} + f_{2})$ (3) $v_{1} + v_{2} = (\frac{2 h}{m} (f_{1} + f_{2}))^{- \frac{1}{2}}$ (4) $v_{1} - v_{2} = (\frac{2 h}{m} (f_{1} - f_{2}))^{1/2}$ 17. $The de-Broglie wavelength associated with an electron and a proton were calculated by accelerating then through same potential of 100 V . What should nearly be the ratio of their wavelengths? (m_{P} = 1.00727 u, m_{e} = 0.00055 u)$ (1) $1860 : 1$ (2) $(1860)^{2} : 1$ (3) $41.4 : 1$ (4) $43 : 1$ 18. $The susceptibility of a ferromagnetic substance is$ (1) $> 1$ (2) $Zero$ (3) $>> 1$ (4) $< 1$ 19. $The susceptibility of A 1 is 2 \times 10^{- 5} . The percent increase in the magnetic field when the space within a current carrying toroid to filled with Al is$ (1) $2 \times 10^{- 2}$ (2) $2 \times 10^{- 3}$ (3) $2 \times 10^{- 4}$ (4) $2 \times 10^{- 5}$ 20. $A bar magnet has coercivity 4 \times 10^{3} Am^{- 1} . It is placed inside a solenoid of 12 cm length and 60 turns. The current that should be passed through the solenoid to demagnetise the bar magnet is$ (1) $2 A$ (2) $4 A$ (3) $6 A$ (4) $8 A$ 21. $Needles N_{1}, N_{2} and N_{3} are made of a ferromagnetic, a paramagnetic and a diamagnetic substance respectively. A magnet when brought close to them will$ (1) $attract all three of them$ (2) $attract N_{1} strongly, N_{2} weakly and repel N_{3} weakly$ (3) $attract N_{1} strongly but repel N_{2} and N_{3} weakly$ (4) $attract N_{1} and N_{2} strongly but repel N_{3}$ 22. $A magnetic dipole of moment 2.5 Am^{2} is free to rotate about a vertical axis passing through its centre. It is released from East-West direction. Its kinetic energy at the moment, it takes North-South position is (B_{H} = 3 \times 10^{- 5} T)$ (1) $50 μJ$ (2) $100 μJ$ (3) $175 μJ$ (4) $75 μJ$ 23. $The ratio of surface tensions of mercury and water is given to be 7.5 while the ratio of their densities is 13.6. Their contact angles, with glass, are close to 135° and 0°, respectively. It is observed that mercury gets depressed by an amount h in a capillary tube of radius r_{1}, while water rises by the same amount h in a capillary tube of radius r_{2} . The ratio, (\frac{r _{1}}{r _{2}}), is then close to:$ (1) $4/5$ (2) $2/5$ (3) $3/5$ (4) $2/3$ 24. $The strength of the Earth's magnetic field is$ (1) $constant everywhere$ (2) $zero everywhere$ (3) $having very high value$ (4) $varying from place to place on the Earth's surface.$ 25. $At certain place, the horizontal component of earth's magnetic field is 3.0 G and the angle of dip at that place is 30^{\circ} . The magnetic field of earth at that location$ (1) $4.5 G$ (2) $5.1 G$ (3) $3.5 G$ (4) $6.0 G$ 26. $Certain galvanometers have a fixed core made of non magnetic metallic material. The function of this metallic material is$ (1) $to oscillate the coil in magnetic field for longer period of time$ (2) $to bring the coil to rest quickly$ (3) $to produce large deflecting torque on the coil$ (4) $to make the magnetic field radial$ 27. $In a ferromagnetic material, below the curie temperature, a domain is defined as:$ (1) $a macroscopic region with consecutive magnetic diploes oriented in opposite direction.$ (2) $a macroscopic region with zero magnetization.$ (3) $a macroscopic region with saturation magnetization.$ (4) $a macroscopic region with randomly oriented magnetic dipoles.$ 28. $A boy’s catapult is made of rubber made of a rubber cord of length 42 cm long, with 6 mm diameter of cross-section and of negligible mass. The boy keeps a stone weighing 0.02 kg on it and stretches the cord by 20 cm by applying a constant force. When released, the stone flies off with a velocity of 20 ms^{- 1} . Neglect the change in the area of cross-section of the cord while stretched. The Young’s modulus of rubber is closest to:$ (1) $10^{6} N / m^{- 2}$ (2) $10^{4} N / m^{- 2}$ (3) $10^{8} N / m^{- 2}$ (4) $10^{3} N / m^{- 2}$ 29. $The net magnetic flux through any closed surface is [NEET 2023]$ (1) $positive$ (2) $infinity$ (3) $negative$ (4) $zero$ 30. $The magnetic field lines of a bar magnet$ (1) $leave from the south pole of the ma$ (2) $are absent inside the magnet$ (3) $intersect each other$ (4) $form continuous closed loops$