Practice Questions

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.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) : When currents vary with time, Newton's third law is valid only if momentum carried by the electromagnetic field is taken into account. Statement (II) : Ampere's circuital law does not depend on Biot-Savart's law. In the light of the above statements, choose the correct answer from the options given below : (1) Both Statement I and Statement II are true (2) Statement I is true but Statement II is false (3) Both Statement I and Statement II are false (4) Statement I is false but Statement II is true

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.In an a.c. circuit, voltage and current are given by: V = 100 sin(100t) V and I = 100 sin(100t + π3 ) mA respectively. The average power dissipated in one cycle is : (1) 5 W (2) 10 W (3) 2. 5 W (4) 25 W

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

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 LCR circuit is at resonance for a capacitor C , inductance L and resistance R. Now the value of resistance is halved keeping all other parameters same. The current amplitude at resonance will be now: JEE Main 2024 (08 Apr Shift 1) JEE Main Previous Year Paper (1) Zero (2) same (3) halved (4) double

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.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 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.A beam of unpolarised light of intensity 𝐼0 is passed through a polaroid 𝐴 and then through another polaroid 𝐵 which is oriented so that its principal plane makes an angle of 45° relative to that of 𝐴. The intensity of emergent light is : (1) 𝐼0 (2) 𝐼0 4 𝐼0 𝐼0 (3) (4) 2 8

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.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.An electron is projected with uniform velocity along the axis inside a current carrying long solenoid. Then : (1) the electron will continue to move with uniform (2) the electron will be accelerated along the axis. velocity along the axis of the solenoid. (3) the electron path will be circular about the axis. (4) the electron will experience a force at 45∘ to the axis and execute a helical path.

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.An AC voltage 𝑉= 20sin200𝜋𝑡 is applied to a series LCR circuit which drives a current 𝐼= 10sin200π𝑡+ 3 . The average power dissipated is: JEE Main 2024 (31 Jan Shift 2) JEE Main Previous Year Paper (1) 21 . 6 W (2) 200 W (3) 173 . 2 W (4) 50 W

Q14.The following figure represents two biconvex lenses L1 and L2 having focal length 10 cm and 15 cm respectively. The distance between L1&L2 is : (1) 10 cm (2) 35 cm (3) 25 cm (4) 15 cm

Q15.A transformer has an efficiency of 80% and works at 10 V and 4 kW . If the secondary voltage is 240 V, then the current in the secondary coil is: (1) 1 . 59 A (2) 13 . 33 A (3) 1 . 33 A (4) 15 . 1 A

Q15.A plane EM wave is propagating along x direction. It has a wavelength of 4 mm . If electric field is in y direction with the maximum magnitude of 60Vm−1 , the equation for magnetic field is : (1) Bz = 2 × 10−7 sin [ π2 × 103 (x −3 × 108t)]^kT (2) Bz = 60 sin [ π2 (x −3 × 108t)]^kT (3) Bx = 60 sin [ π2 (x −3 × 108t)]i ^ T (4) Bz = 2 × 10−7 sin [ π2 (x −3 × 108t)]^kT JEE Main 2024 (09 Apr Shift 1) JEE Main Previous Year Paper

Q15.The deflection in moving coil galvanometer falls from 25 divisions to 5 division when a shunt of 24 Ω is applied. The resistance of galvanometer coil will be: (1) 12 Ω (2) 96 Ω (3) 48 Ω (4) 100 Ω

Q15.The position of the image formed by the combination of lenses is : (1) 15 cm (right of second lens) (2) 30 cm (left of third lens) (3) 15 cm (left of second lens) (4) 30 cm (right of third lens)

Q15.A coil is placed perpendicular to a magnetic field of 5000 T. When the field is changed to 3000 T in 2 s, an induced emf of 22 V is produced in the coil. If the diameter of the coil is 0 . 02 m, then the number of turns in the coil is: (1) 7 (2) 70 (3) 35 (4) 140