Practice Questions

Q10.A charge of 4μC is to be divided into two. The distance between the two divided charges is constant. The magnitude of the divided charges so that the force between them is maximum, will be: (1) 1μC and 3μC (2) 2μC and 2μC (3) 0 and 4μC (4) 1. 5μC and 2. 5μC

Q10.The displacement of simple harmonic oscillator after 3 seconds starting from its mean position is equal to half of its amplitude. The time period of harmonic motion is (1) 12 s (2) 8 s (3) 36 s (4) 6 s

Q10.A long straight wire with a circular cross-section having radius 𝑅, is carrying a steady current 𝐼. The current 𝐼 is uniformly distributed across this cross-section. Then the variation of magnetic field due to current 𝐼 with distance 𝑟𝑟< 𝑅 from its centre will be (1) 𝐵∝𝑟 (2) 𝐵∝1 𝑟 1 (3) 𝐵∝𝑟2 (4) 𝐵∝ 𝑟2

Q11.An observer moves towards a stationary source of sound with a velocity one-fifth of the velocity of sound. The percentage change in the apparent frequency is (1) zero (2) 5% (3) 10% (4) 20%

Q11.The current I in the given circuit will be (1) 10A (2) 20A (3) 4A (4) 40A + T. If it has an acceleration of

Q11.Two point charges A and B of magnitude +8 × 10−6C and −8 × 10−6C respectively are placed at a distance d apart. The electric field at the middle point O between the charges is 6. 4 × 104 N C−1 . The distance ' d' between the point charges A and B is (1) 2 m (2) 3 m (3) 1 m (4) 4 m

Q12.A triangular shaped wire carrying 10 A current is placed in a uniform magnetic field of 0. 5 T, as shown in figure. The magnetic force on segment CD is (Given BC = CD = BD = 5 cm). (1) 0. 126 N (2) 0. 312 N (3) 0. 216 N (4) 0. 245 N

Q12.If the electric potential at any point (x, y, z) m in space is given by V = 3x2 volt. The electric field at the point (1, 0, 3) m will be : (1) 3 Vm−1 , directed along positive x-axis. (2) 3 Vm−1 , directed along negative x-axis. (3) 6 Vm−1 , directed along negative x-axis. (4) 6 Vm−1 , directed along positive x-axis.

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 wattless current flows in the AC circuit, then the circuit is : (1) Purely Resistive circuit (2) Purely Inductive circuit (3) LCR series circuit (4) RC series circuit only 𝑡- 𝑥

Q12.A parallel plate capacitor is formed by two plates each of area 30π cm2 separated by 1 mm. A material of dielectric strength 3. 6 × 107 V m−1 is filled between the plates. If the maximum charge that can be stored on the capacitor without causing any dielectric breakdown is 7 × 10−6 C, the value of dielectric constant of the material is : [Use 1 = 9 × 109 N m2 C−2 ] 4πεo (1) 1. 66 (2) 1. 75 (3) 2. 25 (4) 2. 33

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

Q13.A proton and an alpha particle of the same velocity enter in a uniform magnetic field which is acting perpendicular to their direction of motion. The ratio of the radii of the circular paths described by the alpha particle and proton is (1) 4 : 1 (2) 2 : 1 (3) 1 : 2 (4) 1 : 4

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.Two parallel, long wires are kept 0. 20 m apart in vacuum, each carrying current of x A in the same direction. If the force of attraction per meter of each wire is 2 × 10−6 N , then the value of x is approximately (1) 1 (2) 2. 4 (3) 1. 4 (4) 2

Q14.The susceptibility of a paramagnetic material is 99. The permeability of the material in Wb /A −m, is [Permeability of free space μ0 = 4π × 10−7 Wb /A −m] (1) 4π × 10−5 (2) 4π × 10−6 (3) 4π × 10−7 (4) 4π × 10−4

Q14.The aperture of the objective is 24. 4 cm. The resolving power of this telescope, if a light of wavelength ∘ 2440 A is used to see the object will be (1) 8. 1 × 106 (2) 10. 0 × 107 (3) 8. 2 × 105 (4) 1. 0 × 10−8

Q14.In a series LR circuit XL = R and power factor of the circuit is P1 . When capacitor with capacitance C such that XL = XC is put in series, the power factor becomes P2 . The ratio P1 is P2 (1) 1 (2) 1 2 √2 (3) √3 (4) 2 : 1 √2

Q14.The vertical component of the earth's magnetic field is 6 × 10-5 T at any place where the angle of dip is 37°. 3 The earth's resultant magnetic field at that place will be (Given tan37° = 4) (1) 8 × 10-5 T (2) 6 × 10-5 T (3) 5 × 10-4 T (4) 1 × 10-4 T

Q14.At a certain place the angle of dip is 30° and the horizontal component of earth's magnetic field is 0. 5 G . The earth's total magnetic field (in G), at that certain place, is JEE Main 2022 (29 Jun Shift 1) JEE Main Previous Year Paper (1) 1 (2) 1 √3 2 (3) √3 (4) 1

Q14.A transformer operating at primary voltage 8 kV and secondary voltage 160 V serves a load of 80 kW. Assuming the transformer to be ideal with purely resistive load and working on unity power factor, the loads in the primary and secondary circuit would be (1) 800 Ω and 1. 06 Ω (2) 10 Ω and 500 Ω (3) 800 Ω and 0. 32 Ω (4) 1. 06 Ω and 500 Ω

Q15.The oscillating magnetic field in a plane electromagnetic wave is given by 𝐵𝑦= 5 × 10-6sin1000𝜋5𝑥- 4 × 108𝑡 T. The amplitude of electric field will be (1) 15 × 102Vm-1 (2) 5 × 10-6Vm-1 (3) 16 × 1012Vm-1 (4) 4 × 102Vm-1

Q15.The current flowing through an ac circuit is given by I = 5 sin(120πt) A. How long will the current take to reach the peak value starting from zero? (1) 1 s (2) 60 s 60 (3) 120 1 s (4) 2401 s

Q15.Match List - I with List - II List-I List-II (a) UV rays (i) Diagnostic tool in medicine (b) X -rays (ii) Water purification (c) Microwave (iii) Communication, Radar (d) Infrared wave (iv) Improving visibility in foggy days Choose the correct answer from the options given below : (1) (a) −(iii), (b) −(ii), (c) −(i), (d) −(iv) (2) (a) −(ii), (b) −(i), (c) −(iii), (d) −(iv) (3) (a) −(ii), (b) −(iv), (c) −(iii), (d) −(i) (4) (a) −(iii), (b) −(i), (c) −(ii), (d) −(iv)

Q16.Light wave travelling in air along x-direction is given by Ey = 540 sin π × 104(x −ct) V m−1 . Then, the peak value of magnetic field of wave will be (Given c = 3 × 108 m s−1 ) (1) 18 × 10−7 T (2) 54 × 10−7 T (3) 54 × 10−8 T (4) 18 × 10−8 T