Practice Questions

Q29.A power transmission line feeds input power at 2 . 3 kV to a step down transformer with its primary winding having 3000 turns. The output power is delivered at 230 V by the transformer. The current in the primary of the transformer is 5 A and its efficiency is 90%. The winding of transformer is made of copper. The output current of transformer is ____A.

Q29.Two waves of intensity ratio 1 : 9 cross each other at a point. The resultant intensities at the point, when (a) 𝐼1 10 Waves are incoherent is 𝐼1 𝑏 Waves are coherent is 𝐼2 and differ in phase by 60o. If = 𝑥, then 𝑥= 𝐼2 _________. JEE Main 2024 (31 Jan Shift 1) JEE Main Previous Year Paper

Q29.A parallel beam of monochromatic light of wavelength 600 nm passes through single slit of 0.4 mm width. Angular divergence corresponding to second order minima would be ______ ×10−3rad.

Q29.In a double slit experiment shown in figure, when light of wavelength 400 nm is used, dark fringe is observed at P . If D = 0. 2 m, the minimum distance between the slits S1 and S2 is α mm . Write the value of 10α to the nearest integer. JEE Main 2024 (29 Jan Shift 1) JEE Main Previous Year Paper

Q29.The distance between object and its 3 times magnified virtual image as produced by a convex lens is 20 cm . The focal length of the lens used is ________ cm .

Q29.Light from a point source in air falls on a convex curved surface of radius 20 cm and refractive index 1 . 5. If the source is located at 100 cm from the convex surface, the image will be formed at ______ cm from the object. JEE Main 2024 (31 Jan Shift 2) JEE Main Previous Year Paper

Q29.In a single slit experiment, a parallel beam of green light of wavelength 550 nm passes through a slit of width 0.20 mm. The transmitted light is collected on a screen 100 cm away. The distance of first order minima from the central maximum will be x × 10−5 m . The value of x is : JEE Main 2024 (05 Apr Shift 2) JEE Main Previous Year Paper

Q29.In Young's double slit experiment, monochromatic light of wavelength 5000 A is used. The slits are 1 . 0 mm apart and screen is placed at 1 . 0 m away from slits. The distance from the centre of the screen where intensity becomes half of the maximum intensity for the first time is ______ × 10-6 m .

Q29.The distance between object and its two times magnified real image as produced by a convex lens is 45 cm. The focal length of the lens used is ________ cm .

Q30.Radius of a certain orbit of hydrogen atom is 8.48Ã … . If energy of electron in this orbit is E/x. then x = _____ (Given a0 = 0.529Ã … , E = energy of electron in ground state).

Q30.Monochromatic light of wavelength 500 nm is used in Young's double slit experiment. An interference pattern is obtained on a screen. When one of the slits is covered with a very thin glass plate (refractive index = 1.5 ), the central maximum is shifted to a position previously occupied by the 4th bright fringe. The thickness of the glass-plate is ______ μm .

Q30.In Franck-Hertz experiment, the first dip in the current-voltage graph for hydrogen is observed at 10.2 V. The wavelength of light emitted by hydrogen atom when excited to the first excitation level is _________ nm . (Given hc = 1245eVnm, e = 1.6 × 10−19C ).

Q30.Hydrogen atom is bombarded with electrons accelerated through a potential different of V , which causes excitation of hydrogen atoms. If the experiment is being formed at T = 0 K. The minimum potential difference needed to observe any Balmer series lines in the emission spectra will be α V , where α = 10 _________.(Write the value to the nearest integer)

Q30.A particular hydrogen - like ion emits the radiation of frequency 3 × 1015 Hz when it makes transition from 𝑥 𝑛= 2 to 𝑛= 1 . The frequency of radiation emitted in transition from 𝑛=3 to 𝑛= 1 is × 1015 Hz, when 9 𝑥= _____.

Q30.A potential divider circuit is connected with a dc source of 20 V, a light emitting diode of glow in voltage 1.8 V and a zener diode of breakdown voltage of 3.2 V. The length (PR) of the resistive wire is 20 cm. The minimum length of PQ to just glow the LED is _____ cm

Q30.The shortest wavelength of the spectral lines in the Lyman series of hydrogen spectrum is 915Ã … . The longest wavelength of spectral lines in the Balmer series will be _____ Ã … .

Q30.In a nuclear fission process, a high mass nuclide (A ≈236) with binding energy 7. 6 MeV /Nucleon dissociated into two middle mass nuclides (A ≈118), having binding energy of 8. 6 MeV /Nucleon. The energy released in the process would be _______ MeV .

Q30.If three helium nuclei combine to form a carbon nucleus then the energy released in this reaction is _____ ×10−2MeV . (Given 1u = 931MeV/c2 , atomic mass of helium = 4.002603u )

Q30.If Rydberg's constant is R, the longest wavelength of radiation in Paschen series will be 7𝑅, where 𝛼= ______.

Q30.The disintegration energy Q for the nuclear fission of 235U →140Ce + 94Zr + n is ______ MeV . Given atomic masses of 235U : 235.0439u; 140Ce : 139.9054u, 94Zr : 93.9063u; n : 1.0086u, Value of c2 = 931MeV/u

Q30.In an experiment to measure the focal length ( 𝑓) of a convex lens, the magnitude of object distance ( 𝑥) and the image distance ( 𝑦) are measured with reference to the focal point of the lens. The 𝑦- 𝑥 plot is shown in figure. The focal length of the lens is _____cm .

Q30.In an alpha particle scattering experiment distance of closest approach for the α particle is 4.5 × 10−14 m . If target nucleus has atomic number 80 , then maximum velocity of α - particle is _______ ×105 m/s approximately. = 9 × 109 SI unit, mass of α particle = 6.72 × 10−27 kg) ( 4πϵ01

Q30.The mass defect in a particular reaction is 0 . 4 g. The amount of energy liberated is 𝑛× 107 kW h, where 𝑛= _____. (speed of light = 3 × 108 m s-1)

Q31.The density of ' x ' M solution (' X ' molar) of NaOH is 1.12 g mL−1 , while in molality, the concentration of the solution is 3 m(3molal). Then x is (Given : Molar mass of NaOH is 40 g/mol ) (1) 3.5 (2) 3.8 (3) 2.8 (4) 3.0

Q31.Match List I with List II Choose the correct answer from the options given below :- (1) A-II, B-III, C-I, D-IV (2) A-I, B-III, C-II, D-IV (3) A-II, B-IV, C-III, D-I (4) A-I, B-II, C-III, D-IV