Practice Questions

Q19.Match List I with List II List – I List – II (Current configuration) (Magnetic field at point O ) + A I. B0 = μ0I4πr [π 2] JEE Main 2023 (25 Jan Shift 1) JEE Main Previous Year Paper B II. B0 = μ04 Ir C III. B0 = μ0I2πr [π −1] + D IV. B0 = μ0I4πr [π 1] Choose the correct answer from the option given below: (1) A-III, B-IV, C-I, D-II (2) A-I, B-III, C-IV, D-II (3) A-III, B-I, C-IV, D-II (4) A-II, B-I, C-IV, D-III

Q20.A modulating signal is a square wave, as shown in the figure. If the carrier wave is given as ct = 2sin8𝜋t volts, the modulation index is: 1 (1) (2) 1 4 (3) 1 (4) 1 3 2

Q20.Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: A bar magnet dropped through a metallic cylindrical pipe takes more time to come down compared to a non-magnetic bar with same geometry and mass. Reason R : For the magnetic bar, Eddy currents are produced in the metallic pipe which oppose the motion of the magnetic bar. In the light of the above statements, choose the correct answer from the options given below JEE Main 2023 (11 Apr Shift 2) JEE Main Previous Year Paper (1) A is false but R is true (2) Both A and R are true and R is the correct explanation of A (3) A is true but R is false (4) Both A and R are true and R is NOT the correct explanation of A

Q20.A long conducting wire having a current I flowing through it, is bent into a circular coil of N turns. Then it is bent into a circular coil of n turns. The magnetic field is calculated at the centre of coils in both the cases. The ratio of the magnetic field in first case to that of second case is: (1) N : n (2) n2 : N 2 (3) N 2 : n2 (4) n : N

Q20.Which of the following frequencies does not belong to FM broadcast. (1) 106 𝑀𝐻𝑧 (2) 64 𝑀𝐻𝑧 (3) 99 𝑀𝐻𝑧 (4) 89 𝑀𝐻𝑧

Q20.A sinusoidal carrier voltage is amplitude modulated. The resultant amplitude modulated wave has maximum and minimum amplitude of 120 V and 80 V respectively. The amplitude of each side band is : (1) 15 V (2) 10 V (3) 20 V (4) 5 V

Q20.A transmitting antenna is kept on the surface of the earth. The minimum height of receiving antenna required to receive the signal in line of sight at 4 km distance from it is 𝑥× 10-2 m. The value of 𝑥 is _____. (Let, radius of earth 𝑅= 6400 km) (1) 125 (2) 1250 (3) 12 . 5 (4) 1 . 25

Q20.The height of transmitting antenna is 180 m and the height of the receiving antenna is 245 m . The maximum distance between them for satisfactory communication in line of sight will be: (given R = 6400 km ) JEE Main 2023 (15 Apr Shift 1) JEE Main Previous Year Paper (1) 96 km (2) 56 km (3) 48 km (4) 104 km

Q20.A square loop of area 25 cm2 has a resistance of 10 Ω . The loop is placed in uniform magnetic field of magnitude 40. 0 T . The plane of loop is perpendicular to the magnetic field. The work done in pulling the loop out of the magnetic field slowly and uniformly in 1. 0 sec, will be JEE Main 2023 (29 Jan Shift 2) JEE Main Previous Year Paper (1) 2. 5 × 10−3 J (2) 1. 0 × 10−3 J (3) 1. 0 × 10−4 J (4) 5 × 10−3 J

Q20.Two cells are connected between points A and B as shown. Cell 1 has emf of 12 V and internal resistance of 3 Ω. Cell 2 has emf of 6 V and internal resistance of 6 Ω. An external resistor R of 4 Ω is connected across A and B. The current flowing through R will be ______ A .

Q20.The source of time varying magnetic field may be (A) a permanent magnet (B) an electric field changing linearly with time (C) direct current (D) a decelerating charge particle (E) an antenna fed with a digital signal Choose the correct answer from the options given below. (1) (C) and (E) only (2) (D) only (3) (A) only (4) (B) and (D) only

Q20.In an experiment with vernier callipers of least count 0 . 1 mm, when two jaws are joined together the zero of vernier scale lies right to the zero of the main scale and 6th division of vernier scale coincides with the main scale division. While measuring the diameter of a spherical bob, the zero of vernier scale lies in between 3 . 2 cm and 3 . 3 cm marks and 4th division of vernier scale coincides with the main scale division. The diameter of bob is measured as (1) 3 . 22 cm (2) 3 . 18 cm (3) 3 . 26 cm (4) 3 . 25 cm JEE Main 2023 (10 Apr Shift 2) JEE Main Previous Year Paper

Q20.The ratio of magnetic field at the centre of a current carrying coil of radius r to the magnetic field at distance r from the centre of coil on its axis is √x : 1 . The value of x is _____.

Q20.Certain galvanometers have a fixed core made of non magnetic metallic material. The function of this metallic material is JEE Main 2023 (08 Apr Shift 1) JEE Main Previous Year Paper (1) to oscillate the coil in magnetic field for longer (2) to bring the coil to rest quickly period of time (3) to produce large deflecting torque on the coil (4) to make the magnetic field radial

Q20.By what percentage will the transmission range of a TV tower be affected when the height of the tower is increased by 21%? (1) 15% (2) 12% (3) 10% (4) 14%

Q21.The speed of a swimmer is 4 km h-1 in still water. If the swimmer makes his strokes normal to the flow of river of width 1 km, he reaches a point 750 m down the stream on the opposite bank. The speed of the river water is ______ km h-1.

Q21.A horse rider covers half the distance with 5 m s-1 speed. The remaining part of the distance was travelled with speed 10 m s-1 for half the time and with speed 15 m s-1 for other half of the time. The mean 𝑥 speed of the rider averaged over the whole time of motion is m s-1. The value of 𝑥 is ______. 7

Q21.If the maximum load carried by an elevator is 1400 kg ( 600 kg-Passengers + 800 kg-elevator ) , which is moving up with a uniform speed of 3 m s-1 and the frictional force acting on it is 2000 N, then the maximum power used by the motor is _____________kW . 𝑔= 10 m s-2

Q21.In the given figure, an inductor and resistor are connected in series with a battery of emf E volt. Ea2b J s−1 represents the maximum rate at which the energy is stored in the magnetic field (inductor). The numerical value of b will be _____. a JEE Main 2023 (13 Apr Shift 1) JEE Main Previous Year Paper

Q21.For a moving coil galvanometer, the deflection in the coil is 0. 05 rad when a current of 10 mA is passed through it. If the torsional constant of suspension wire is 4. 0 × 10–5 N m rad−1 , the magnetic field is 0. 01 T and the number of turns in the coil is 200 , the area of each turn (in cm2 ) is : (1) 2. 0 (2) 1. 0 (3) 1. 5 (4) 0. 5

Q21.A closed circular tube of average radius 15 cm, whose inner walls are rough, is kept in vertical plane. A block of mass 1 kg just fit inside the tube. The speed of block is 22 m s-1, when it is introduced at the top of tube. After completing five oscillations, the block stops at the bottom region of tube. The work done by the tube on the block is ________ J. (Given 𝑔= 10 m s-2).

Q21.A proton with a kinetic energy of 2. 0 eV moves into a region of uniform magnetic field of magnitude π 2 × 10−3 T. The angle between the direction of magnetic field and velocity of proton is 60o . The pitch of the helical path taken by the proton is ____ cm. (Take, mass of proton = 1. 6 × 10−27 kg and charge on proton = 1. 6 × 10−19 C).

Q21.In an ac generator, a rectangular coil of 100 turns each having area 14 × 10–2 m2 is rotated at 360 rev min−1 about an axis perpendicular to a uniform magnetic field of magnitude 3. 0 T. The maximum value of the emf produced will be ______ V . [Take π = 227 ]

Q21.For the given figures, choose the correct options: (1) The rms current in circuit (b) can never be larger (2) The rms current in figure (a) is always equal to than that in (a) that in figure (b) (3) The rms current in circuit (b) can be larger than (4) At resonance, current in (b) is less than that in (a) that in (a)

Q21.A projectile fired at 30° to the ground is observed to be at same height at time 3 s and 5 s after projection, during its flight. The speed of projection of the projectile is m s-1. (Given 𝑔= 10 m s-2) →