Practice Questions

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.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.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

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.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.The half-life of a radioactive nucleus is 5 years. The fraction of the original sample that would decay in 15 years is : (1) 1 (2) 1 8 4 (3) 7 (4) 3 8 4

Q19.The logic performed by the circuit shown in figure is equivalent to JEE Main 2023 (11 Apr Shift 1) JEE Main Previous Year Paper (1) AND (2) NOR (3) OR (4) NAND

Q19.The effect of increase in temperature on the number of electrons in conduction band ( 𝑛𝑒) and resistance of a semiconductor will be as: JEE Main 2023 (31 Jan Shift 1) JEE Main Previous Year Paper (1) Both 𝑛𝑒 and resistance decrease (2) Both 𝑛𝑒 and resistance increase (3) 𝑛𝑒 increases, resistance decreases (4) 𝑛𝑒 decreases, resistance increases

Q19.The output from a NAND gate having inputs A and B given below will be, (1) (2) (3) (4)

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

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.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.A compass needle oscillates 20 times per minute at a place where the dip is 30o and 30 times per minute where the dip is 60o . The ratio of total magnetic field due to the earth at two places respectively is 4 . The value of √x x is

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.A current carrying rectangular loop PQRS is made of uniform wire. The length PR = QS = 5 cm and PQ = RS = 100 cm. If ammeter current reading changes from I to 2I , the ratio of : f PQ)2I is: magnetic forces per unit length on the wire PQ due to wire RS in the two cases respectively (f PQI JEE Main 2023 (30 Jan Shift 2) JEE Main Previous Year Paper (1) 1 : 2 (2) 1 : 4 (3) 1 : 5 (4) 1 : 3

Q20.To radiate EM signal of wavelength 𝜆 with high efficiency, the antennas should have a minimum size equal to: (1) 2𝜆 (2) 𝜆 2 (3) 𝜆 (4) 𝜆 4

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.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 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.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.As shown in the figure the voltmeter reads 2 V across 5 Ω resistor. The resistance of the voltmeter is _____ Ω

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.Find the mutual inductance in the arrangement, when a small circular loop of wire of radius R is placed inside a large square loop of wire of side L(L ≫R) . The loops are coplanar and their centres coincide : JEE Main 2023 (29 Jan Shift 1) JEE Main Previous Year Paper (1) M = √2μ0R2L (2) M = 2√2μ0RL2 (3) M = 2√2μ0R2L (4) M = √2μ0RL2