Practice Questions

Q12.A battery of 6 V is connected to the circuit as shown below. The current 𝐼 drawn from the battery is (1) 1 A (2) 2 A (3) 6 A (4) 4 A 11 3 JEE Main 2022 (26 Jul Shift 2) JEE Main Previous Year Paper

Q13.Two bar magnets oscillate in a horizontal plane in earth's magnetic field with time periods of 3 s and 4 s respectively. If their moments of inertia are in the ratio of 3 : 2 then the ratio of their magnetic moments will be (1) 2 : 1 (2) 8 : 3 (3) 1 : 3 (4) 27 : 16

Q13.A cyclotron is used to accelerate protons. If the operating magnetic field is 1. 0 T and the radius of the cyclotron 'dees' is 60 cm, the kinetic energy of the accelerated protons in MeV will be : [use mp = 1. 6 × 10−27 kg, e = 1. 6 × 10−19 C] (1) 12 (2) 18 (3) 16 (4) 32

Q13.An electron with energy 0. 1 keV moves at right angle to the earth's magnetic field of 1 × 10−4 Wbm−2 . The frequency of revolution of the electron will be (Take mass of electron = 9. 0 × 10−31 kg) (1) 1. 6 × 105 Hz (2) 5. 6 × 105 Hz (3) 2. 8 × 106 Hz (4) 1. 8 × 106 Hz

Q13.A parallel plate capacitor filled with a medium of dielectric constant 10 , is connected across a battery and is charged. The dielectric slab is replaced by another slab of dielectric constant 15 . Then the energy of capacitor will (1) increase by 50% (2) decrease by 15% (3) increase by 25% (4) increase by 33%

Q13.If a charge q is placed at the centre of a closed hemispherical non-conducting surface, the total flux passing through the flat surface would be JEE Main 2022 (27 Jun Shift 2) JEE Main Previous Year Paper (1) q (2) q ε0 2ε0 (3) q (4) q 4ε0 2πε0

Q13.A 1 m long wire is broken into two unequal parts 𝑋 and 𝑌. The 𝑋 part of the wire is stretched into another wire 𝑊. Length of 𝑊 is twice the length of 𝑋 and the resistance of 𝑊 is twice that of 𝑌. Find the ratio of length JEE Main 2022 (29 Jul Shift 2) JEE Main Previous Year Paper of 𝑋 and𝑌. (1) 1: 4 (2) 1: 2 (3) 4: 1 (4) 2: 1

Q13. BX and BY are the magnetic field at the centre of two coils of two coils X and Y respectively, each carrying equal current. If coil X has 200 turns and 20 cm radius and coil Y has 400 turns and 20 cm radius, the ratio of BX and BY is JEE Main 2022 (26 Jul Shift 1) JEE Main Previous Year Paper (1) 1 : 1 (2) 1 : 2 (3) 2 : 1 (4) 4 : 1

Q13.If the charge on a capacitor is increased by 2C , the energy stored in it increases by 44%. The original charge on the capacitor is (in C ) (1) 10 (2) 20 (3) 30 (4) 40

Q13.Two concentric circular loops of radii 𝑟1 = 30 cm and 𝑟2 = 50 cm are placed in 𝑋- 𝑌 plane as shown in the figure. A current 𝐼= 7 A is flowing through them in the direction as shown in figure. The net magnetic moment of this system of two circular loops is approximately (1) 7 ^𝑘 A m2 (2) -7 ^𝑘 A m2 2 2 (3) 7 ^𝑘 A m2 (4) -7 ^𝑘 A m2 → →

Q13.The electric field in an electromagnetic wave is given by 𝐸= 56 . 5sin𝜔 𝑐NC-1. Find the intensity of the wave if it is propagating along 𝑥-axis in the free space. (Given 𝜖0 = 8 . 85 × 10-12C2 N-1 m-2) (1) 5 . 65Wm-2 (2) 1 . 9 × 10-7Wm-2 (3) 4 . 24 Wm-2 (4) 56 . 5Wm-2

Q13.A 72 Ω galvanometer is shunted by a resistance of 8 Ω. The percentage of the total current which passes through the galvanometer is (1) 0. 1% (2) 10% (3) 25% (4) 0. 25%

Q13.A sinusoidal voltage 𝑉𝑡= 210sin3000𝑡 volt is applied to a series LCR circuit in which 𝐿= 10 mH, 𝐶= 25 μF and 𝑅= 100Ω. The phase difference 𝛷 between the applied voltage and resultant current will be (1) tan-10 . 17 (2) tan-19 . 46 (3) tan-10 . 30 (4) tan-113 . 33

Q13.An alternating emf E = 440 sin 100πt is applied to a circuit containing an inductance of √2π H . If an a.c. ammeter is connected in the circuit, its reading will be : (1) 4. 4 A (2) 1. 55 A (3) 2. 2 A (4) 3. 11 A

Q13.The refracting angle of a prism is A and refractive index of the material of the prism is cot( A2 ). Then the angle of minimum deviation will be (1) 180°−2A (2) 90°−A (3) 180°+2A (4) 180°−3A

Q13.Two identical cells each of emf 1. 5 V are connected in parallel across a parallel combination of two resistors each of resistance 20 Ω. A voltmeter connected in the circuit measures 1. 2 V . The internal resistance of each cell is : (1) 2. 5 Ω (2) 4 Ω (3) 5 Ω (4) 10 Ω

Q13.A capacitor is discharging through a resistor R. Consider in time t1 , the energy stored in the capacitor reduces to half of its initial value and in time t2 , the charge stored reduces to one eighth of its initial value. The ratio t2t1 will be (1) 1 (2) 1 2 3 (3) 1 (4) 1 4 6

Q13.The magnetic field at the center of current carrying circular loop is B1 . The magnetic field at a distance of √3 times radius of the given circular loop from the center on its axis is B2 . The value of B1B2 will be (1) 9 : 4 (2) 12 : √5 (3) 8 : 1 (4) 5 : √3

Q14.Three identical charged balls each of charge 2C are suspended from a common point P by silk threads of 2 m each (as shown in figure). They form an equilateral triangle of side 1 m . The ratio of net force on a charged ball to the force between any two charged balls will be (1) √3 : 1 (2) √3 : 2 (3) 1 : 1 (4) 1 : 4

Q14.A direct current of 4 A and an alternating current of peak value 4 A flow through resistance of 3 Ω and 2 Ω respectively. The ratio of heat produced in the two resistances in same interval of time will be : (1) 3 : 2 (2) 3 : 1 (3) 3 : 4 (4) 4 : 3

Q14.The equation of current in a purely inductive circuit is 5sin49𝜋𝑡- 30°. If the inductance is 30mH then the equation for the voltage across the inductor, will be (1) 1 . 47sin49𝜋𝑡- 30° (2) 1 . 47sin49𝜋𝑡+ 60° (3) 23 . 1sin49𝜋𝑡- 30° (4) 23 . 1sin49𝜋𝑡+ 60°

Q14.The electric current in a circular coil of 2 turns produces a magnetic induction B1 at its centre. The coil is unwound and is rewound into a circular coil of 5 turns and the same current produces a magnetic induction B2 JEE Main 2022 (25 Jul Shift 2) JEE Main Previous Year Paper at its centre. The ratio of B2 is: B1 (1) 5 (2) 25 2 4 (3) 5 (4) 25 4 2

Q14.Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : In an uniform magnetic field, speed and energy remains the same for a moving charged particle. Reason (R): Moving charged particle experiences magnetic force perpendicular to its direction of motion. JEE Main 2022 (24 Jun Shift 1) JEE Main Previous Year Paper (1) Both Assertion and Reason are true and Reason is (2) Both Assertion and Reason are true but Reason is the correct explanation of Assertion. NOT the correct explanation of Assertion. (3) Assertion is true but Reason is false. (4) Assertion is false but Reason is true.

Q14.The magnetic flux through a coil perpendicular to its plane is varying according to the relation ϕ = (5t3 + 4t2 + 2t −5) Weber. If the resistance of the coil is 5 ohm , then the induced current through the coil at t = 2 s will be, (1) 15. 6 A (2) 16. 6 A (3) 17. 6 A (4) 18. 6 A

Q14.The electromagnetic waves travel in a medium at a speed of 2 . 0 × 108 m s-1. The relative permeability of the medium is 1 . 0. The relative permittivity of the medium will be (1) 2 . 25 (2) 4 . 25 (3) 6 . 25 (4) 8 . 25