Practice Questions

Q24.A Young's double-slit experiment is performed using monochromatic light of wavelength λ. The intensity of light at a point on the screen, where the path difference is λ, is K units. The intensity of light at a point where the path difference is λ is given by nK , where n is an integer. The value of n is 6 12

Q24.In a Young's double slit experiment 15 fringes are observed on a small portion of the screen when light of wavelength 500 nm is used. Ten fringes are observed on the same section of the screen when another light source of wavelength λ is used. Then the value of λ is (in nm ) __________.

Q25.When radiation of wavelength A is used to illuminate a metallic surface, the stopping potential is V . When the same surface is illuminated with radiation of wavelength 3A , the stopping potential is V4 . If the threshold wavelength for the metallic surface is nλ then value of n will be :

Q25.Both the diodes used in the circuit shown are assumed to be ideal and have negligible resistance when these are forward biased. Built in potential in each diode is 0.7V . For the input voltages shown in the figure, the JEE Main 2020 (09 Jan Shift 1) JEE Main Previous Year Paper voltage (in Volts) at point A is ________

Q25.A light ray enters a solid glass sphere of refractive index μ = √3 at an angle of incidence 60°. The ray is both reflected and refracted at the farther surface of the sphere. The angle (in degrees) between the reflected and refracted rays at this surface is _____________.

Q25.A beam of electromagnetic radiation of intensity 6.4 × 10−5W/cm2 is comprised of wavelength, λ = 310nm . It falls normally on a metal (work function φ = 2eV ) of surface area of 1cm2 . If one in 103 photons ejects an election, total number of electrons ejected in 1s is 10x . (hc = 1240eVnm, 1eV = 1.6 × 10−19J), then x is ___________

Q25.When an object is kept at a distance of 30 cm from a concave mirror, the image is formed at a distance of 10 cm from the mirror. If the object is moved with a speed of 9 cm s−1 , the speed (in cm s−1 ) with which image moves at that instant is

Q25.Orange light of wavelength 6000 × 10–10 m illuminates a single slit of width 0. 6 × 10–4 m. The maximum possible number of diffraction minima produced on both sides of the central maximum is __________

Q25.The surface of a metal is illuminated alternately with photons of energies E1 = 4 eV and E2 = 2. 5 eV respectively. The ratio of maximum speeds of the photoelectrons emitted in the two cases is 2. The work function of the metal in (eV) is..........

Q25.A point object in air is in front of the curved surface of a plano-convex lens. The radius of curvature of the curved surface is 30 cm and the refractive index of the lens material is 1.5, then the focal length of the lens (in cm) is ___________. 1 − (I) to n2

Q25.In the line spectra of hydrogen atom, difference between the largest and the shortest wavelengths of the Lyman ∘ ∘ series is 305 A . The corresponding difference for the Paschan series in A is:________

Q25.An observer can see through a small hole on the side of a jar (radius 15 cm ) at a point at height of 15 cm from the bottom (see figure). The hole is at a height of 45 cm. When the jar is filled with a liquid up to a height of 30 cm the same observer can see the edge at the bottom of the jar. If the refractive index of the liquid is N , where N is an integer, the value of N is 100 JEE Main 2020 (03 Sep Shift 1) JEE Main Previous Year Paper

Q25.The first member of the Balmer series of hydrogen atom has a wavelength of 6561 A . The wavelength of the second member of the Balmer series (in nm) is_____________

Q25.The output characteristics of a transistor is shown in the figure. When VCE is 10V and IC = 4 .0 mA , then value of βac is JEE Main 2020 (06 Sep Shift 2) JEE Main Previous Year Paper

Q25.A part of a complete circuit is shown in the figure. At some instant, the value of current I is 1A and it is decreasing at a rate of 102 As−1 . The value of the potential difference Vp −VQ, (in volts) at that instant is-

Q25.The balancing length for a cell is 560cm in a potentiometer experiment. When an external resistance of 10Ω is connected in parallel to the cell, the balancing length changes by 60cm . If the internal resistance of the cell is n Ω , where n is an integer then value of n is ________ 10

Q25.In the circuit shown below, is working as a 8 V dc regulated voltage source. When 12 V is used as an input, the power dissipated (in mW ) in each diode is (Considering both zener diodes are identical)

Q25.A beam of electrons of energy E scatters from a target having atomic spacing of 1 Å . The first maximum intensity occurs at θ = 60°. Then E(in eV) is........ (Planck's constant h = 6. 64 × 10−34 Js, 1 eV = 1. 6 × 10−19J, electron mass m = 9. 1 × 10−31 kg)

Q26.The ammonia (NH3) released on quantitative reaction of 0.6 g urea (NH2CONH2) with sodium hydroxide (NaOH) can be neutralized by (1) 200 ml of 0.4 NHCl (2) 200 ml of 0.2 NHCl (3) 100 ml of 0.2 NHCl (4) 100 ml of 0.1 NHCl

Q26.The figure that is not a direct manifestation of the quantum nature of atom is : (1) (2) (3) (4)

Q26.The de Broglie wavelength of an electron in the 4th Bohr orbit is: (1) 2πa0 (2) 4πa0 (3) 6πa0 (4) 8πa0

Q26.The number of subshells associated with n = 4 and m = −2 quantum numbers is: (1) 8 (2) 2 (3) 16 (4) 4

Q26.The correct statement about probability density (except at infinite distance from nucleus) is : (1) It can be zero for 1s orbital (2) It can be negative for 2p orbital (3) It can be zero for 3p orbital (4) It can never be zero for 2s orbital

Q26.The strengths of 5. 6 volume hydrogen peroxide (of density 1 g/ mL ) in terms of mass percentage and molarity (M) respectively, are: (Take molar mass of hydrogen peroxide as 34 g/ mol) (1) 1.7 and 0.5 (2) 0.85 and 0.25 (3) 1.7 and 0.25 (4) 0.85 and 0.5

Q26.Amongst the following statements, that which was not proposed by Dalton was : (1) chemical reactions involve reorganization of (2) all the atoms of a given element have identical atoms. These are neither created nor destroyed in properties including identical mass. Atoms of a chemical reaction. different elements differ in mass. (3) when gases combine or reproduced in a chemical (4) matter consists of indivisible atoms. reaction they do so in a simple ratio by volume provided all gases are at the same T & P.