Practice Questions

Q24.The length of a wire becomes 𝑙1 and 𝑙2 when 100 N and 120 N tension are applied respectively. If 1 10𝑙2 = 11𝑙1, then the natural length of wire will be 𝑥𝑙1. Here the value of 𝑥 is 𝜋

Q24.A scientist is observing a bacteria through a compound microscope. For better analysis and to improve its resolving power he should. (Select the best option) (1) Increase the wave length of the light (2) Increase the refractive index of the medium between the object and objective lens (3) Decrease the focal length of the eye piece (4) Decrease the diameter of the objective lens

Q24.The energy density associated with electric field E and magnetic field B of an electromagnetic wave in free space is given by ( ε0− permittivity of free space, μ0− permeability of free space) (1) UE = 2ε0E2 , UB = 2μ0 B2 (2) UE = ε0E22 , UB = 2μ0B2 μ0B2 , UB = 2 (3) UE = ε0E22 , UB = μ0B22 (4) UE = 2ε0E2

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.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.When one light ray is reflected from a plane mirror with 30° angle of reflection, the angle of deviation of the ray after reflection is: JEE Main 2023 (11 Apr Shift 2) JEE Main Previous Year Paper (1) 120° (2) 110° (3) 140° (4) 130°

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.

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 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.The threshold wavelength for photoelectric emission from a material is 5500 A . Photoelectrons will be emitted, when this material is illuminated with monochromatic radiation from a A. 75 W infra-red lamp B. 10 W infra-red lamp C. 75 W ultra-violet lamp D. 10 W ultra-violet lamp Choose the correct answer from the options given below : (1) B and C only (2) A and D only (3) C only (4) C and D only

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.Match List I and List II → → A Gauss’s Law in Electrostatics I ∮ E ⋅ dl = −dϕBdt → → B Faraday's Law II ∮ B ⋅d A = 0 → → C Gauss’s Law in Magnetism III ∮ B ⋅d l = μ0ic + μ0 ∈0 dϕEdt q D Ampere-Maxwell Law IV ∮→E ⋅d→s= ∈0 Choose the correct answer from the options given below : (1) A-IV, B-I, C-II, D-III (2) A-I, B-II, C-III, D-IV (3) A-III, B-IV, C-I, D-II (4) A-II, B-III, C-IV, D-I JEE Main 2023 (25 Jan Shift 2) JEE Main Previous Year Paper

Q25.The equation of wave is given by 𝑌= 10-2sin2𝜋160𝑡- 0 . 5𝑥+ 4, where 𝑥 and 𝑌 are in 𝑚 and 𝑡 in 𝑠. The speed of the wave is _______ km h-1.

Q25.Two equal positive point charges are separated by a distance 2𝑎. The distance of a point from the centre of the line joining two charges on the equatorial line (perpendicular bisector) at which force experienced by a test charge becomes maximum is 𝑎 The value of 𝑥 is ______. 𝑞0 √𝑥. JEE Main 2023 (01 Feb Shift 1) JEE Main Previous Year Paper

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.An electron revolves around an infinite cylindrical wire having uniform linear charge density 2 × 10-8 C m-1 in circular path under the influence of attractive electrostatic field as shown in the figure. The velocity of electron with which it is revolving is ______________ × 106 m s-1. Given mass of electron = 9 × 10-31 kg

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

Q25.The difference between threshold wavelengths for two metal surfaces A and B having work function ϕA = 9 eV and ϕB = 4. 5 eV in nm is: {Given, hc = 1242 eV nm } (1) 540 (2) 276 (3) 264 (4) 138

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.The width of fringe is 2 mm on the screen in a double slit experiment for the light of wavelength of 400 nm. The width of the fringe for the light of wavelength 600 nm will be: (1) 4 mm (2) 2 mm (3) 1. 33 mm (4) 3 mm