Practice Questions

Q19.As shown in the figure, a current of 2 A flowing in an equilateral triangle of side 4√3 cm . The magnetic field at the centroid O of the triangle is : (Neglect the effect of earth’s magnetic field) (1) 4√3 × 10−4 T (2) 4√3 × 10−5 T (3) √3 × 10−4 T (4) 3√3 × 10−5 T

Q19.The output waveform of the given logical circuit for the following inputs 𝐴 and 𝐵 as shown below, is JEE Main 2023 (30 Jan Shift 1) JEE Main Previous Year Paper (1) (2) (3) (4)

Q19.Figure shows a part of an electric circuit. The potentials at points a, b and c are 30 V, 12 V and 2 V respectively. The current through the 20 Ω resistor will be, (1) 1. 0 A (2) 0. 4 A (3) 0. 6 A (4) 0. 2 A

Q19.A long solenoid is formed by winding 70 turns cm−1 . If 2. 0 A current flows, then the magnetic field produced inside the solenoid is ______________. (µ0 = 4π × 10–7 T m A–1) (1) 1232 × 10–4 T (2) 176 × 10–4 T (3) 352 × 10–4 T (4) 88 × 10–4 T

Q19.For the given circuit, in the steady state, |VB −VD| = _____ V .

Q19.Match the List I with List II List I List II AIntrinsic I Fermi-level near valence band Semiconductor Fermi-level at middle of valence and conduction B n-type semiconductor II band C p-type semiconductor III Fermi-level near conduction band DMetals IVFermi-level inside conduction band Choose the correct answer from the options given below: (1) (A) → I, (B) → II, (C) → III, (D) → IV (2) (A) → II, (B) → I, (C) → III, (D) → IV (3) (A) → II, (B) → III, (C) → I, (D) → IV (4) (A) → III, (B) → I, (C) → II, (D) → IV

Q19.The magnitude of magnetic induction at mid-point O due to current arrangement as shown in figure will be . (1) μ0I (2) 0 2πa (3) μ0I (4) μ0I 4πa πa

Q19.When a resistance of 5 Ω is shunted with a moving coil galvanometer, it shows a full scale deflection for a current of 250 mA, however when 1050 Ω resistance is connected with it in series, it gives full scale deflection for 25 volt. The resistance of galvanometer is _________Ω.

Q19.The resistance of a wire is 5 Ω. Its new resistance in ohm, if stretched to 5 times of its original length will be : JEE Main 2023 (25 Jan Shift 2) JEE Main Previous Year Paper (1) 625 (2) 125 (3) 5 (4) 25

Q19.A current of 2 A flows through a wire of cross-sectional area 25. 0 mm2 . The number of free electrons in a cubic meter are 2. 0 × 1028 . The drift velocity of the electrons is _____ ×10−6 ms−1 (given, charge on electron = 1. 6 × 10−19C).

Q19.The electric current in a circular coil of four turns produces a magnetic induction 32 T at its centre. The coil is unwound and is rewound into a circular coil of single turn, the magnetic induction at the centre of the coil by the same current will be : (1) 8 T (2) 4 T (3) 2 T (4) 16 T

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

Q19.A zener diode of power rating 1 . 6 W is to be used as voltage regulator. If the zener diode has a breakdown of 8 V and it has to regulate voltage fluctuating between 3 V and 10 V The value of resistance 𝑅𝑠 for safe operation of diode will be (1) 10 Ω (2) 12 Ω (3) 13 . 3 Ω (4) 13 Ω

Q19.In the given circuit the value of I1+I3 is: I2

Q19.Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Photodiodes are preferably operated in reverse bias condition for light intensity measurement. Reason R: The current in the forward bias is more than the current in the reverse bias for a 𝑝- 𝑛 junction diode. In the light of the above statement, choose the correct answer from the options given below : JEE Main 2023 (24 Jan Shift 1) JEE Main Previous Year Paper (1) A is false but R is true (2) Both A and R are true but R is NOT the correct explanation of A (3) A is true but R is false (4) Both A and R are true and R is the correct explanation of A

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.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.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.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.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.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.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%

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 .