Practice Questions

Q13.What will be the magnitude of the electric field at point O as shown in the figure? Each side of the figure is l and perpendicular to the other? (1) 1 q (2) 1 q 4πε0 l2 4πε0 (2l2) (2√2 −1) (3) q (4) 1 2q 4πε0(2l)2 4πε0 2l2 (√2)

Q13.For the given circuit, comment on the type of transformer used : (1) Auxilliary transformer (2) Auto transformer (3) Step-up transformer (4) Step down transformer

Q14.Consider the diffraction pattern obtained from the sunlight incident on a pinhole of diameter 0. 1 μm. If the diameter of the pinhole is slightly increased, it will affect the diffraction pattern such that (1) its size increases, and intensity increases (2) its size decreases, and intensity decreases (3) its size decreases, but intensity increases (4) its size increases, but intensity decreases

Q14.An inductor coil stores 64 J of magnetic field energy and dissipates energy at the rate of 640 W when a current of 8 A is passed through it. If this coil is joined across an ideal battery, find the time constant of the circuit (in s). (1) 0. 4 (2) 0. 2 (3) 0. 125 (4) 0. 8

Q14.Match List-I with List-II. List - I List - II (a) ωL > ωC1 (i) Current is in phase with emf (b) ωL = ωC1 (ii) Current lags behind the applied emf (c) ωL < ωC1 (iii) Maximum current occurs (d) Resonant frequency (iv) Current leads the emf Choose the correct answer from the options given below. (1) (a) - (ii) ; (b) - (i) ; (c) - (iv) ; (d) - (iii) (2) (a) - (ii) ; (b) - (i) ; (c) - (iii) ; (d) - (iv) (3) (a) - (iii) ; (b) - (i) ; (c) - (iv); (d) - (ii) (4) (a) - (iv) ; (b) - (iii) ; (c) - (ii); (d) - (i)

Q14.Following plots show Magnetization ( 𝑀) vs Magnetising field ( 𝐻) and Magnetic susceptibility ( χ ) vs Temperature ( 𝑇) graph : Which of the following combination will be represented by a diamagnetic material? (1) ( b ) , ( c ) (2) ( b ) , ( d ) (3) ( a ) , ( d ) (4) ( a ) , ( c )

Q14.In the reported figure, a capacitor is formed by placing a compound dielectric between the plates of parallel plate capacitor. The expression for the capacity of the said capacitor will be: (Given the area of the plate = A ) (1) 15 Kε0 A (2) 15 Kε0 A 34 d 6 d (3) 25 Kε0 A (4) 9 Kε0 A 6 d 6 d

Q14.The angular frequency of alternating current in a L-C-R circuit is 100 rad s−1 . The components connected are shown in the figure. Find the value of inductance of the coil and capacity of condenser. (1) 1. 33 H and 150 μF (2) 0. 8 H and 150 μF (3) 1. 33 H and 250 μF (4) 0. 8 H and 250 μF

Q14.In an ac circuit, an inductor, a capacitor and a resistor are connected in series with XL = R = XC. Impedance of this circuit is : (1) Zero (2) R (3) R√2 (4) 2R2 JEE Main 2021 (31 Aug Shift 1) JEE Main Previous Year Paper

Q14.A coaxial cable consists of an inner wire of radius a surrounded by an outer shell of inner and outer radii b and c respectively. The inner wire carries an electric current i0 which is distributed uniformly across cross- sectional area. The outer shell carries an equal current in opposite direction and distributed uniformly. What will be the ratio of the magnetic field at a distance x from the axis when (i) x < a and (ii) a < x < b ? (1) a2 (2) b2−a2 x2 x2 (3) x2 (4) x2 b2−a2 a2

Q14.If you are provided a set of resistances, 2 Ω, 4 Ω, 6 Ω and 8 Ω. Connect these resistances to obtain an equivalent resistance of 46 3 Ω. (1) 2 Ω and 6 Ω are in parallel with 4 Ω and 8 Ω in series (2) 4 Ω and 6 Ω are in parallel with 2 Ω and 8 Ω in series (3) 2 Ω and 4 Ω are in parallel with 6 Ω and 8 Ω in series (4) 6 Ω and 8 Ω are in parallel with 2 Ω and 4 Ω in series

Q14.Your friend is having eye sight problem. She is not able to see clearly a distant uniform window mesh and it appears to her as nonuniform and distorted. The doctor diagnosed the problem as : (1) Astigmatism (2) Myopia with Astigmatism (3) Presbyopia with Astigmatism (4) Myopia and hypermetropia

Q14.A current through a wire depends on time as 𝑖= 𝛼0𝑡+ 𝛽𝑡2, where 𝛼0 = 20 A s-1 and 𝛽= 8 A s-2. Find the charge crossed through a section of the wire in 15 s . (1) 2250 C (2) 11250 C (3) 2100 C (4) 260 C

Q14.A bar magnet is passing through a conducting loop of radius R with velocity v. The radius of the bar magnet is such that it just passes through the loop. The induced e.m.f. in the loop can be represented by the approximate curve: (1) (2) (3) (4)

Q14.The arm PQ of a rectangular conductor is moving from x = 0 to x = 2b outwards and then inwards from x = 2b to x = 0 as shown in the figure. A uniform magnetic field perpendicular to the plane is acting from x = 0 to x = b. Identify the graph showing the variation of different quantities with distance: (1) A —Flux, B—Power dissipated, C —EMF (2) A —Power dissipated, B—Flux, C—EMF (3) A —Flux, B—EMF , C —Power dissipated (4) A—EMF , B—Power dissipated, C —Flux

Q14.A conducting bar of length L is free to slide on two parallel conducting rails as shown in the figure → Two resistors R1 and R2 are connected across the ends of the rails. There is a uniform magnetic field B pointing into the page. An external agent pulls the bar to the left at a constant speed v. The correct statement about the directions of induced currents I1 and I2 flowing through R1 and R2 respectively is : (1) Both I1 and I2 are in anticlockwise direction (2) Both I1 and I2 are in clockwise direction (3) I1 is in clockwise direction and I2 is in (4) I1 is in anticlockwise direction and I2 is in anticlockwise direction clockwise direction

Q14.Match List - I with List - II. List-I List-II (a) Source of microwave frequency (i) Radioactive decay of nucleus (b) Source of infrared frequency (ii) Magnetron (c) Source of Gamma Rays (iii) Inner shell electrons (d) Source of X -rays (iv) Vibration of atoms and molecules (v) LASER (vi) RC circuit Choose the correct answer from the options given below: (1) (a)-(ii), (b)-(iv), (c)-(vi), (d)-(iii) (2) (a)-(vi), (b)-(iv), (c)-(i), (d)-(v) (3) (a)-(vi), (b)-(v), (c)-(i), (d)-(iv) (4) (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)

Q14.An aeroplane, with its wings spread 10 m, is flying at a speed of 180 km h−1 in a horizontal direction. The total intensity of earth's field at that part is 2. 5 × 10−4 Wb m−2 and the angle of dip is 60°. The emf induced JEE Main 2021 (26 Feb Shift 2) JEE Main Previous Year Paper between the tips of the plane wings will be (1) 108. 25 mV (2) 54. 125 mV (3) 88. 37 mV (4) 62. 50 mV

Q14.In a series LCR circuit, the inductive reactance (XL) is 10 Ω and the capacitive reactance (XC) is 4 Ω. The resistance (R) in the circuit is 6 Ω. The power factor of the circuit is : (1) 21 (2) 2√21 (3) 1 (4) √3 √2 2 JEE Main 2021 (18 Mar Shift 2) JEE Main Previous Year Paper

Q14.With what speed should a galaxy move outward with respect to earth so that the sodium- D line at wavelength ∘ ∘ 5890 A is observed at 5896 A? (1) 306 km sec−1 (2) 322 km sec−1 (3) 296 km sec−1 (4) 336 km sec−1

Q14.A current of 1 . 5 A is flowing through a triangle, of side 9 cm each. The magnetic field at the centroid of the triangle is : (Assume that the current is flowing in the clockwise direction.) (1) 2√3 × 10-5 T, inside the plane of triangle (2) 2√3 × 10-7 T, outside the plane of triangle (3) 3 × 10-7 T, outside the plane of triangle (4) 3 × 10-5 T, inside the plane of triangle

Q14.A hairpin like shape as shown in figure is made by bending a long current carrying wire. What is the magnitude of a magnetic field at point P which lies on the centre of the semicircle ? (1) μ0I + 4πr (2 −π) (2) μ0I4πr (2 π) (3) μ0I + 2πr (2 π) (4) μ0I2πr (2 −π)

Q14.The given potentiometer has its wire of resistance 10 Ω. When the sliding contact is in the middle of the potentiometer wire, the potential drop across 2 Ω resistor is: (1) 10 V (2) 5 V (3) 40 9 V (4) 4011 V

Q14.In the Young's double slit experiment, the distance between the slits varies in time as 𝑑𝑡= 𝑑0 + 𝑎0 sin𝜔𝑡; where 𝑑0, 𝜔 and 𝑎0 are constants. The difference between the largest fringe width and the smallest fringe width obtained over time is given as: (1) 2𝜆𝐷𝑑02 2 (2) 2𝜆𝐷𝑎02 2 𝑑0 - 𝑎0 𝑑0 - 𝑎0 𝜆𝐷 (3) 𝜆𝐷 2𝑎0 (4) 𝑑0 + 𝑎0 𝑑0

Q14.The resistance of a conductor at 15°C is 16 Ω and at 100°C is 20 Ω. What will be the temperature coefficient of resistance of the conductor? (1) 0. 010°C−1 (2) 0. 033°C−1 (3) 0. 003°C−1 (4) 0. 042°C−1