Practice Questions

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 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.

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.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.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.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.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.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.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.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.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.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.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.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.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)

Q1. In the equation 𝑋+ 𝑎 𝑏] = 𝑅𝑇, 𝑋 is pressure, 𝑌 is volume, 𝑅 is universal gas constant and 𝑇 is 𝑌2[𝑌- temperature. The physical quantity equivalent to the ratio 𝑎 is: 𝑏 (1) Pressure gradient (2) Energy (3) Impulse (4) Coefficient of viscosity

Q1. Two resistance are given as 𝑅1 = ( 10 ± 0 . 5 ) Ω and 𝑅2 = ( 15 ± 0 . 5 ) Ω . The percentage error in the measurement of equivalent resistance when they are connected in parallel is (1) 6 . 33 (2) 2 . 33 (3) 5 . 33 (4) 4 . 33

Q1. Three forces F1 = 10 N, F2 = 8 N, F3 = 6 N are acting on a particle of mass 5 kg. The forces F2 and F3 are applied perpendicularly so that particle remains at rest. If the force F1 is removed, then the acceleration of the particle is (1) 7 m s–2 (2) 0. 5 m s–2 (3) 4. 8 m s–2 (4) 2 m s–2

Q1. Two trains A and B of length l and 4l are travelling into a tunnel of length L in parallel tracks from opposite directions with velocities 108 km h−1 and 72 km h−1, respectively. If train A take 35 s less time than train B to cross the tunnel then, length L of tunnel is: (Given L = 60 l) (1) 1200 m (2) 900 m (3) 1800 m (4) 2700 m

Q1. A body is moving with constant speed, in a circle of radius 10 m. The body completes one revolution in 4 s. At the end of 3rd second, the displacement of body (in m) from its starting point is: (1) 30 (2) 15 π (3) 5 π (4) 10√2

Q1. If the velocity of light c, universal gravitational constant G and planck's constant h are chosen as fundamental quantities. The dimensions of mass in the new system is: 2 c 2 G1] (2) h1c1G−1 (1) [h 1 1 2 c 2 G 2 ] (4) [h 2 c 2 G−12 ] (3) [h−1 1 1 1 1

Q1. If P = 3ˆi + √3ˆj + 2ˆk and Q = 4ˆi + √3ˆj + 2. 5ˆk then, the unit vector in the direction of P × Q is x is x 1 (√3ˆi +ˆj −2√3ˆk). The value of

Q1. In an experiment of measuring the refractive index of a glass slab using travelling microscope in physics lab, a student measures real thickness of the glass slab as 5. 25 mm and apparent thickness of the glass slab at 5. 00 mm . Travelling microscope has 20 divisions in one cm on main scale and 50 divisions on Vernier scale is equal to 49 divisions on main scale. The estimated uncertainty in the measurement of refractive index of the slab is x × 10−3 , where x is ______ 10

Q1. A cylindrical wire of mass (0. 4 ± 0. 01) g has length (8 ± 0. 04) cm and radius (6 ± 0. 03) mm . The maximum error in its density will be (1) 3. 5% (2) 5% (3) 1% (4) 4%