Practice Questions

Q12.Given below two statements : One is labelled as Assertion (A) and other is labelled as Reason (R). Assertion (A): Non-polar materials do not have any permanent dipole moment. Reason (R): When a non-polar material is placed in an electric field, the centre of the positive charge distribution of it's individual atom or molecule coincides with the centre of the negative charge distribution. In the light of above statements, choose the most appropriate answer from the options given below. (1) Both (A) and (R) are correct and (R) is the (2) Both (A) and (R) are correct and (R) is not the correct explanation of (A). correct explanation of (A). (3) (A) is correct but (R) is not correct. (4) (A) is not correct but (R) is correct.

Q12.The current sensitivity of a galvanometer can be increased by : (A) decreasing the number of turns (B) increasing the magnetic field (C) decreasing the area of the coil (D) decreasing the torsional constant of the spring Choose the most appropriate answer from the options given below : (1) (B) and (C) only (2) (C) and (D) only (3) (A) and (C) only (4) (B) and (D) only

Q12.If a wave gets refracted into a denser medium, then which of the following is true? (1) Wavelength, speed and frequency decreases. (2) Wavelength increases, speed decreases and frequency remains constant. (3) Wavelength and speed decreases but frequency (4) Wavelength, speed and frequency increases. remains constant.

Q12.A long solenoid carrying a current produces a magnetic field 𝐵 along its axis. If the current is doubled and the number of turns per cm is halved, the new value of magnetic field will be equal to JEE Main 2022 (25 Jun Shift 2) JEE Main Previous Year Paper (1) 2𝐵 (2) 4𝐵 𝐵 (3) (4) 𝐵 2

Q12.A charge particle is moving in a uniform magnetic field (2ˆi 3ˆj) m s−2 , then the value of α will be (αˆi −4ˆj) (1) 3 (2) 6 (3) 12 (4) 2

Q12.A compass needle of oscillation magnetometer oscillates 20 times per minute at a place P of dip 30° . The number of oscillations per minute become 10 at another place Q of 60° dip. The ratio of the total magnetic field at the two places (BQ : BP) is: (1) √3 : 4 (2) 4 : √3 (3) √3 : 2 (4) 2 : √3 JEE Main 2022 (27 Jul Shift 2) JEE Main Previous Year Paper

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.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.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.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.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

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.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 bar magnet having a magnetic moment of 2. 0 × 105 J T−1 , is placed along the direction of uniform magnetic field of magnitude B = 14 × 10−5 T. The work done in rotating the magnet slowly through 60° from the direction of field is (1) 14 J (2) 8 J (3) 4 J (4) 1. 4 J ∘

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.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.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.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 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. 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.As shown in the figure, a metallic rod of linear density 0 . 45 kg m-1 is lying horizontally on a smooth incline plane which makes an angle of 45° with the horizontal. The minimum current flowing in the rod required to keep it stationary, when 0 . 15 T magnetic field is acting on it in the vertical upward direction, will be (Use 𝑔= 10 m s-2) (1) 30 A (2) 15 A (3) 10 A (4) 3 A JEE Main 2022 (28 Jul Shift 1) JEE Main Previous Year Paper

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.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.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.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