Practice Questions

Q13.The magnetic moment of a bar magnet is 0.5Am2 . It is suspended in a uniform magnetic field of 8 × 10−2 T. The work done in rotating it from its most stable to most unstable position is: (1) 8 × 10−2 J (2) 4 × 10−2 J (3) Zero (4) 16 × 10−2 J JEE Main 2024 (04 Apr Shift 2) JEE Main Previous Year Paper

Q13.To measure the internal resistance of a battery, potentiometer is used. For R = 10Ω, the balance point is observed at l = 500 cm and for R = 1Ω the balance point is observed at l = 400 cm. The internal resistance of the battery is approximately : (1) 0.2Ω (2) 0.3Ω (3) 0.4Ω (4) 0.1Ω

Q13.In an ammeter, 5% of the main current passes through the galvanometer. If resistance of the galvanometer is G, the resistance of ammeter will be: G G (1) (2) 20 199 (3) 199 G (4) 200 G

Q13.A uniform magnetic field of 2 × 10-3 T acts along positive Y-direction. A rectangular loop of sides 20 cm and 10 cm with current of 5 A is in Y-Z plane. The current is in anticlockwise sense with reference to negative X axis. Magnitude and direction of the torque is : (1) 2 × 10-4 N m along positive Z –direction (2) 2 × 10-4 N m along negative Z-direction (3) 2 × 10-4 N m along positive X-direction (4) 2 × 10-4 N m along positive Y-direction π

Q13.The magnetic field in a plane electromagnetic wave is By = (3.5 × 10−7) sin (1.5 × 103x + 0.5 × 1011t)T. The corresponding electric field will be : (1) Ey = 10.5 sin (1.5 × 103x + 0.5 × 1011t)Vm−1 (2) Ez = 1.17 sin (1.5 × 103x + 0.5 × 1011t)Vm−1 (3) Ey = 1.17 sin (1.5 × 103x + 0.5 × 1011t)Vm−1 (4) Ez = 105 sin (1.5 × 103x + 0.5 × 1011t)Vm−1

Q13.In the given figure R1 = 10Ω, R2 = 8Ω, R3 = 4Ω and R4 = 8Ω . Battery is ideal with emf 12 V . Equivalent resistant of the circuit and current supplied by battery are respectively : (1) 10.5Ω and 1.14 A (2) 12Ω and 1 A (3) 10.5Ω and 1 A (4) 12Ω and 11.4 A

Q13. The equivalent resistance between A and B is : (1) 18Ω (2) 19Ω (3) 25Ω (4) 27Ω

Q13.A long straight wire of radius a carries a steady current I. The current is uniformly distributed across its cross section. The ratio of the magnetic field at a and 2a from axis of the wire is : 2 (1) 1 : 4 (2) 1 : 1 (3) 3 : 4 (4) 4 : 1

Q13.Two charges 𝑞 and 3𝑞 are separated by a distance ‘𝑟’ in air. At a distance 𝑥 from charge 𝑞, the resultant electric field is zero. The value of 𝑥 is : (1) ( 1 + √3 ) (2) 𝑟 𝑟 3 ( 1 + √3 ) 𝑟 (3) (4) 𝑟( 1 + √3 ) ( 1 + √3 ) JEE Main 2024 (31 Jan Shift 1) JEE Main Previous Year Paper

Q14.A rectangular loop of length 2. 5 m and width 2 m is placed at 60° to a magnetic field of 4 T. The loop is removed from the field in 10 sec. The average emf induced in the loop during this time is (1) −2 V (2) +2 V (3) +1 V (4) −1 V

Q14.The primary side of a transformer is connected to 230 V, 50 Hz supply. The turn ratio of primary to secondary winding is 10 : 1. Load resistance connected to the secondary side is 46 Ω. The power consumed in it is: (1) 12 . 5 W (2) 10 . 0 W (3) 11 . 5 W (4) 12 . 0 W

Q14.A series LR circuit connected with an ac source E = (25 sin 1000t) V has a power factor of 1 . If the source √2 of emf is changed to E = (20 sin 2000t) V, the new power factor of the circuit will be : (1) 1 (2) 1 √2 √3 (3) 1 (4) 1 √5 √7

Q14.Given below are two statements: Statement I: In an LCR series circuit, current is maximum at resonance. Statement II: Current in a purely resistive circuit can never be less than that in a series LCR circuit when connected to same voltage source. In the light of the above statements, choose the correct from the options given below: (1) Statement I is false but Statement II is true (2) Statement I is true but Statement II is false (3) Both Statement I and Statement II are true (4) Both Statement I and Statement II are false

Q14.A galvanometer having coil resistance 10 Ω shows a full scale deflection for a current of 3 mA . For it to measure a current of 8 A , the value of the shunt should be: (1) 3 × 10−3Ω (2) 4. 85 × 10−3Ω (3) 3. 75 × 10−3Ω (4) 2. 75 × 10−3Ω

Q14.In the given electromagnetic wave Ey = 600 sin(ωt −kx)Vm−1 , intensity of the associated light beam is (in W/m2 : (Given ϵ0 = 9 × 10−12C2 N−1 m−2 ) (1) 243 (2) 729 (3) 972 (4) 486

Q14.A parallel plate capacitor has a capacitance 𝐶= 200 pF. It is connected to 230 V ac supply with an angular frequency 300 rad s-1. The rms value of conduction current in the circuit and displacement current in the capacitor respectively are : JEE Main 2024 (01 Feb Shift 1) JEE Main Previous Year Paper (1) 1 .38 μA and 1 .38 μA (2) 14 .3 μA and 143 μA (3) 13 .8 μA and 138 μA (4) 13 .8 μA and 13 .8 μA

Q14.To measure the temperature coefficient of resistivity α of a semiconductor, an electrical arrangement shown in the figure is prepared. The arm BC is made up of the semiconductor. The experiment is being conducted at 25°C and resistance of the semiconductor arm is 3 m𝛺. Arm BC is cooled at a constant rate of 2 °C s-1. If the galvanometer G shows no deflection after 10 s, then α is: (1) -2 × 10-2 ∘C-1 (2) -1 . 5 × 10-2 ∘C-1 (3) -1 × 10-2 ∘C-1 (4) -2 . 5 × 10-2 ∘C-1

Q14.In a co-axial straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero : (1) outside the cable (2) inside the outer conductor (3) inside the inner conductor (4) in between the two conductors

Q14.A series LCR circuit is subjected to an ac signal of 200 V, 50 Hz. If the voltage across the inductor (L = 10mH) is 31.4 V, then the current in this circuit is _____ . (1) 68 A (2) 63 A (3) 10 A (4) 10 mA JEE Main 2024 (05 Apr Shift 2) JEE Main Previous Year Paper

Q14. Match List I with List II Choose the correct answer from the options given below: (1) A-I. B-IV, C-II, D-III (2) A-IV. B-I. C-II. D-III (3) A-IV. B-I, C-III, D-II (4) A-I. B-IV, C-III, D-II

Q14.A rigid wire consists of a semicircular portion of radius 𝑅 and two straight sections. The wire is partially immerged in a perpendicular magnetic field 𝐵= 𝐵0 ^j as shown in figure. The magnetic force on the wire if it has a current 𝑖 is : (1) -𝑖𝐵𝑅 ^j (2) 2𝑖𝐵𝑅 ^j (3) 𝑖𝐵𝑅 ^j (4) -2𝑖𝐵𝑅 ^ j

Q14.A coil of negligible resistance is connected in series with 90Ω resistor across 120 V, 60 Hz supply. A voltmeter reads 36 V across resistance. Inductance of the coil is : JEE Main 2024 (08 Apr Shift 2) JEE Main Previous Year Paper (1) 0.286H (2) 0.76H (3) 2.86H (4) 0.91H

Q15.An object is placed in a medium of refractive index 3. An electromagnetic wave of intensity 6 × 108 W m-2 falls normally on the object and it is absorbed completely. The radiation pressure on the object would be (speed of light in free space = 3 × 108 m s-1 ): (1) 36 N m-2 (2) 18 N m-2 (3) 6 N m-2 (4) 2 N m-2

Q15.A plane electromagnetic wave propagating in x-direction is described by Ey = (200 V m−1) sin[1. 5 × 107t −0. 05x]; The intensity of the wave is : (Use ϵ0 = 8. 85 × 10−12 C2 N−1 m−2 ) (1) 35. 4 W m−2 (2) 53. 1 W m−2 (3) 26. 6 W m−2 (4) 106. 2 W m−2

Q15.If the total energy transferred to a surface in time 𝑡 is 6 . 48 × 105 J, then the magnitude of the total momentum delivered to this surface for complete absorption will be : (1) 2 . 46 × 10-3 kg m s-1 (2) 2 . 16 × 10-3 kg m s-1 (3) 1 . 58 × 10-3 kg m s-1 (4) 4 . 32 × 10-3 kg m s-1