Practice Questions

Q24.A series LCR circuit is connected to an AC source of 220 V , 50 Hz. The circuit contains a resistance R = 80 Ω, an inductor of inductive reactance XL = 70 Ω, and a capacitor of capacitive reactance XC = 130 Ω . The power factor of circuit is x . The value of x is: 10

Q24.A fish rising vertically upward with a uniform velocity of 8 m s–1, observes that a bird is diving vertically downward towards the fish with the velocity of 12 m s–1. If the refractive index of water is 34 , then the actual velocity of the diving bird to pick the fish, will be __________m s−1.

Q24.As shown in figures, three identical polaroids P1 , P2 and P3 are placed one after another. The pass axis of P2 and P3 are inclined at angle of 60º and 90º with respect to axis of P1 . The source S has an intensity of 256 W m−2 . The intensity of light at point O is _____ W m−2 . ∘

Q24.In an experiment with sonometer when a mass of 180 g is attached to the string, it vibrates with fundamental frequency of 30 Hz. When a mass 𝑚 is attached, the string vibrates with fundamental frequency of 50 Hz. The value of 𝑚 is ______ g.

Q24.A ray of light is incident from air on a glass plate having thickness √3 cm and refractive index √2 . The angle of incidence of a ray is equal to the critical angle for glass-air interface. The lateral displacement of the ray when it passes through the plate is ____ × 10−2 cm . (given sin 15°= 0. 26 )

Q25.In the figure given below. a block of mass 𝑀= 490 g placed on a frictionless table is connected with two springs having same spring constant (𝐾= 2 N m-1). If the block is horizontally displaced through 𝑋 m then the number of complete oscillations it will make in 14𝜋 seconds will be ______.

Q25.As shown in the figure, in Young's double slit experiment, a thin plate of thickness t = 10 μm and refractive index μ = 1. 2 is inserted infront of slit S1 . The experiment is conducted in air ( μ = 1 ) and uses a monochromatic light of wavelength λ = 500 nm. Due to the insertion of the plate, central maxima is shifted by a distance of xβ0 . β0 is the fringe-width before the insertion of the plate. The value of the x is ______.

Q25.In the following circuit, the magnitude of current 𝐼1, is ______ A. JEE Main 2023 (30 Jan Shift 1) JEE Main Previous Year Paper - 1 A s-1, then the value of 𝑉AB at this instant will be ______ V.

Q25.A person driving car at a constant speed of 15 m s-1 is approaching a vertical wall. The person notices a change of 40 Hz in the frequency of his car’s horn upon reflection from the wall. The frequency of horn is _______Hz . (Given: Speed of sound: 30 m s-1)

Q25.In the given figure the total charge stored in the combination of capacitors is 100 µC. The value of ‘ x’ is ______________.

Q25.Unpolarised light is incident on the boundary between two dielectric media, whose dielectric constants are 2. 8 (medium – 1) and 6. 8 (medium – 2), respectively. To satisfy the condition, so that the reflected and refracted 1 rays are perpendicular to each other, the angle of incidence should be tan−1 (1 + 10θ ) 2 , the value of θ is ______. (Given for dielectric media, μr = 1 )

Q25.A point source of 100 W emits light with 5% efficiency. At a distance of 5 m from the source, the intensity produced by the electric field component is: (1) 1 W (2) 1 W 2π m2 40π m2 1 (3) 10π m2 W (4) 201 m2W

Q25.A convex lens of refractive index 1. 5 and focal length 18 cm in air is immersed in water. The change in focal length of the lens will be_____ cm. (Given refractive index of water = 43 )

Q25.A 2 meter long scale with least count of 0. 2 cm is used to measure the locations of objects on an optical bench. While measuring the focal length of a convex lens, the object pin and the convex lens are placed at 80 cm mark and 1 m mark, respectively. The image of the object pin on the other side of lens coincides with image pin that is kept at 180 cm mark. The % error in the estimation of focal length is: JEE Main 2023 (06 Apr Shift 2) JEE Main Previous Year Paper (1) 0. 85 (2) 1. 70 (3) 1. 02 (4) 0. 51

Q25.In Young's double slits experiment, the position of 5th bright fringe from the central maximum is 5 cm . The distance between slits and screen is 1 m and wavelength of used monochromatic light is 600 nm . The separation between the slits is: (1) 60 μm (2) 48 μm (3) 12 μm (4) 36 μm

Q25.Two light waves of wavelengths 800 and 600 nm are used in Young's double slit experiment to obtain interference fringes on a screen placed 7 m away from plane of slits. If the two slits are separated by 0. 35 mm , then shortest distance from the central bright maximum to the point where the bright fringes of the two wavelength coincide will be ______ mm.

Q25.Two vertical parallel mirrors A and B are separated by 10 cm. A point object O is placed at a distance of 2 cm from mirror A. The distance of the second nearest image behind mirror A from the mirror A is _______ cm.

Q25.Three point charges 𝑞, - 2𝑞 and 2𝑞 are placed on 𝑥 axis at a distance 𝑥= 0, 𝑥= 3 and 𝑥= 𝑅 respectively 4𝑅 from origin as shown. If 𝑞= 2 × 10-6 C and 𝑅= 2 cm, the magnitude of net force experienced by the charge -2𝑞 is _____ N.

Q25.Three concentric spherical metallic shells 𝑋, 𝑌 and 𝑍 of radius 𝑎, 𝑏 and 𝑐 respectively 𝑎< 𝑏< 𝑐 have surface charge densities 𝜎, – 𝜎 and 𝜎, respectively. The shells 𝑋 and 𝑍 are at same potential. If the radii of 𝑋 & 𝑌 are 2 cm and 3 cm, respectively. The radius of shell 𝑍 is _____cm. Q26.10 resistors each of resistance 10 Ω can be connected in such as to get maximum and minimum equivalent resistance. The ratio of maximum and minimum equivalent resistance will be________.

Q25.A block of mass 2 kg is attached with two identical springs of spring constant 20 N m-1 each. The block is placed on a frictionless surface and the ends of the springs are attached to rigid supports (see figure). When the mass is displaced from its equilibrium position, it executes a simple harmonic motion. The time period of oscillation is 𝜋 in SI unit. The value of 𝑋 is______. √𝑋 JEE Main 2023 (24 Jan Shift 1) JEE Main Previous Year Paper 𝑞

Q25.Two convex lenses of focal length 20 cm each are placed coaxially with a separation of 60 cm between them. The image of the distant object formed by the combination is at _____ cm from the first lens.

Q26.The threshold frequency of metal is f0 . When the light of frequency 2f0 is incident on the metal plate, the maximum velocity of photoelectron is v1 . When the frequency of incident radiation is increased to 5f0 . the maximum velocity of photoelectrons emitted is v2 . The ratio of v1 to v2 is: (1) v1 v2 = 21 (2) v2v1 = 81 (3) v1 v2 = 161 (4) v2v1 = 41

Q26.Expression for an electric field is given by →𝐸= 4000 𝑥2 ^i V m-1. The electric flux through the cube of side 20 cm when placed in electric field (as shown in the figure) is ______ V cm. JEE Main 2023 (31 Jan Shift 1) JEE Main Previous Year Paper

Q26.As per the given figure, if d𝑡=d𝐼

Q26.The radius of 2nd orbit of He+ of Bohr's model is r1 and that of fourth orbit of Be3+ is represented as r2. Now the ratio r2 is x : 1. The value of x is _____. r1 Q27. 238 92 A →23490 B + 42D + Q In the given nuclear reaction, the approximate amount of energy released will be: [Given, mass of 238 92 A = 238. 05079 × 931. 5 MeV c−2 , mass of 23490B = 234. 04363 × 931. 5 MeV c−2 , mass of 42D = 4. 00260 × 931. 5 Me V c−2 ] (1) 3. 82 MeV (2) 5. 9 MeV (3) 2. 12 MeV (4) 4. 25 MeV