Practice Questions

Q16.A hydrogen atom in ground state is given an energy of 10.2eV. How many spectral lines will be emitted due to transition of electrons? (1) 6 (2) 3 (3) 10 (4) 1

Q17.The de Broglie wavelengths of a proton and an 𝛼 particle are 𝜆 and 2𝜆 respectively. The ratio of the velocities of proton and 𝛼 particle will be : (1) 1 : 8 (2) 1 : 2 (3) 4 : 1 (4) 8 : 1

Q17.A microwave of wavelength 2 . 0 cm falls normally on a slit of width 4 . 0 cm . The angular spread of the central maxima of the diffraction pattern obtained on a screen 1 . 5 m away from the slit, will be: (1) 30 º (2) 15 º (3) 60 º (4) 45 º

Q17.The refractive index of a prism with apex angle 𝐴 is 𝑐𝑜𝑡 2. The angle of minimum deviation is : (1) 𝛿𝑚= 180° - 𝐴 (2) 𝛿𝑚= 180° - 3𝐴 (3) 𝛿𝑚= 180° - 4𝐴 (4) 𝛿𝑚= 180° - 2𝐴

Q17.Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Number of photons increases with increase in frequency of light. Reason R: Maximum kinetic energy of emitted electrons increases with the frequency of incident radiation. In the light of the above statements, choose the most appropriate answer from the options given below: (1) Both A and R are correct and R is the correct (2) Both A and R are correct and R is NOT the explanation of A. correct explanation of A. (3) A is not correct but R is correct. (4) A is correct but R is not correct.

Q17.In a photoelectric effect experiment a light of frequency 1 . 5 times the threshold frequency is made to fall on the surface of photosensitive material. Now if the frequency is halved and intensity is doubled, the number of photo electrons emitted will be: (1) Doubled (2) Quadrupled (3) Zero (4) Halved

Q17.An effective power of a combination of 5 identical convex lenses which are kept in contact along the principal axis is 25D. Focal length of each of the convex lens is : JEE Main 2024 (04 Apr Shift 1) JEE Main Previous Year Paper (1) 20 cm (2) 50 cm (3) 500 cm (4) 25 cm

Q17.Light emerges out of a convex lens when a source of light kept at its focus. The shape of wavefront of the light is : (1) both spherical and cylindrical (2) plane (3) spherical (4) cylindrical JEE Main 2024 (05 Apr Shift 1) JEE Main Previous Year Paper

Q17.The diffraction pattern of a light of wavelength 400 nm diffracting from a slit of width 0. 2 mm is focused on the focal plane of a convex lens of focal length 100 cm. The width of the 1st secondary maxima will be : (1) 2 mm (2) 2 cm (3) 0. 02 mm (4) 0. 2 mm

Q17.A biconvex lens of refractive index 1. 5 has a focal length of 20 cm in air. Its focal length when immersed in a liquid of refractive index 1. 6 will be: (1) −16 cm (2) −160 cm (3) +160 cm (4) +16 cm

Q17.Which of the following phenomena does not explain by wave nature of light. A. reflection B. diffraction C. photoelectric effect D. interference E. polarization Choose the most appropriate answer from the options given below: (1) E only (2) B, D only (3) C only (4) A, C only

Q17.Which of the following statement is not true about stopping potential (V0) ? (1) It is 1/ e times the maximum kinetic energy of (2) It increases with increase in intensity of the electrons emitted. incident light. (3) It depends on the nature of emitter material. (4) It depends upon frequency of the incident light.

Q17.A nucleus at rest disintegrates into two smaller nuclei with their masses in the ratio of 2 : 1 . After disintegration they will move : (1) in the same direction with same speed. (2) in opposite directions with the same speed. (3) in opposite directions with speed in the ratio of (4) in opposite directions with speed in the ratio of 2 : 1 respectively. 1 : 2 respectively.

Q17.If Mo is the mass of isotope 125 B, MP and Mn are the masses of proton and neutron, then nuclear binding energy of isotope is : (1) (Mo −5Mp)C 2 (2) (5Mp + 7Mn −Mo)C 2 (3) (M0 −12Mn)C 2 (4) (Mo −5Mp −7Mn)C 2

Q17.The threshold frequency of a metal with work function 6 . 63 eV is : (1) 16 × 1015 Hz (2) 16 × 1012 Hz (3) 1 . 6 × 1012 Hz (4) 1 . 6 × 1015 Hz

Q17.Average force exerted on a non-reflecting surface at normal incidence is 2.4 × 10−4 N. If 360 W/cm2 is the light energy flux during span of 1 hour 30 minutes, Then the area of the surface is: (1) 0.2 m2 (2) 20 m2 (3) 0.1 m2 (4) 0.02 m2

Q17.In Young's double slit experiment, light from two identical sources are superimposing on a screen. The path difference between the two lights reaching at a point on the screen is 7λ . The ratio of intensity of fringe at this 4 point with respect to the maximum intensity of the fringe is: (1) 1 (2) 3 2 4 (3) 1 (4) 1 3 4

Q17.An electron revolving in 𝑛th Bohr orbit has magnetic moment 𝜇𝑛. If 𝜇𝑛 ∝ 𝑛𝑥, the value of 𝑥 is: (1) 2 (2) 1 (3) 3 (4) 0

Q17.A convex lens of focal length 40 cm forms an image of an extended source of light on a photoelectric cell. A current I is produced. The lens is replaced by another convex lens having the same diameter but focal length 20 cm. The photoelectric current now is (1) I (2) 4I 2 (3) 2I (4) I

Q17.A proton, an electron and an alpha particle have the same energies. Their de-Broglie wavelengths will be compared as : (1) λα < λp < λe (2) λe > λα > λp (3) λp > λe > λα (4) λp < λe < λα

Q17.When UV light of wavelength 300 nm is incident on the metal surface having work function 2.13eV, electron emission takes place. The stopping potential is: (Given hc = 1240eVnm ) (1) 1.5 V (2) 4.1 V (3) 2 V (4) 4 V

Q18.Monochromatic light of frequency 6 × 1014 Hz is produced by a laser. The power emitted is 2 × 10-3 W . How many photons per second on an average, are emitted by the source? (Given h = 6 . 63 × 10-34 J s) (1) 9 × 1018 (2) 6 × 1015 (3) 5 × 1015 (4) 7 × 1016

Q18.In a nuclear fission reaction of an isotope of mass 𝑀, three similar daughter nuclei of same mass are formed. The speed of a daughter nuclei in terms of mass defect 𝛥𝑀 will be : JEE Main 2024 (30 Jan Shift 2) JEE Main Previous Year Paper (1) 2𝑐𝛥𝑀 (2) 𝛥𝑀𝑐2 √ 𝑀 3 (3) 2𝛥𝑀 (4) 3𝛥𝑀 𝑐√ 𝑀 𝑐√ 𝑀

Q18.The minimum energy required by a hydrogen atom in ground state to emit radiation in Balmer series is nearly : (1) 1 . 5 eV (2) 13 . 6 eV (3) 1 . 9 eV (4) 12 . 1 eV

Q18.When a metal surface is illuminated by light of wavelength 𝜆, the stopping potential is 8 V. When the same surface is illuminated by light of wavelength 3𝜆, stopping potential is 2 V. The threshold wavelength for this surface is : (1) 5𝜆 (2) 3𝜆 (3) 9𝜆 (4) 4 . 5𝜆