Practice Questions

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.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.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.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.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.Two sources of light emit with a power of 200 W. The ratio of number of photons of visible light emitted by each source having wavelengths 300 nm and 500 nm respectively, will be : (1) 1 : 5 (2) 1 : 3 (3) 5 : 3 (4) 3 : 5

Q18.The work function of a substance is 3. 0 eV. The longest wavelength of light that can cause the emission of photoelectrons from this substance is approximately: (1) 215 nm (2) 414 nm (3) 400 nm (4) 200 nm

Q18.The radius of third stationary orbit of electron for Bohr's atom is R. The radius of fourth stationary orbit will be: (1) 4 R (2) 16 R 3 9 (3) 3 R (4) 9 R 4 16

Q18.The ratio of the shortest wavelength of Balmer series to the shortest wavelength of Lyman series for hydrogen atom is : (1) 4 : 1 (2) 1 : 4 (3) 2 : 1 (4) 1 : 2 JEE Main 2024 (06 Apr Shift 1) JEE Main Previous Year Paper

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.The energy released in the fusion of 2 kg of hydrogen deep in the sun is EH and the energy released in the fission of 2 kg of 235U is EU . The ratio EHEU is approximately: (Consider the fusion reaction as 4 ∣H + 2e−→42He + 2v + 6γ + 26.7MeV, energy released in the fission reaction of 235U is 200MeV per fission nucleus and NA = 6.023 × 1023) JEE Main 2024 (09 Apr Shift 2) JEE Main Previous Year Paper (1) 7.62 (2) 25.6 (3) 15.04 (4) 9.13

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 angular momentum of an electron in a hydrogen atom is proportional to : (Where r is the radius of orbit of electron) (1) r (2) √r (3) 1 (4) 1 √r r

Q18.The energy equivalent of 1 g of substance is : (1) 5.6 × 1012MeV (2) 5.6 × 1026MeV (3) 11.2 × 1024MeV (4) 5.6eV

Q18.Which figure shows the correct variation of applied potential difference (V) with photoelectric current (I) at two different intensities of light (I1 < I2) of same wavelengths : (1) (2) (3) (4)

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

Q18.In a hypothetical fission reaction 92X 236 →56Y 141 + 36Z 92 + 3R The identity of emitted particles ( R) is : (1) Electron (2) Neutron (3) γ -radiations (4) Proton 1

Q18.The de-Broglie wavelength of an electron is the same as that of a photon. If velocity of electron is 25% of the velocity of light, then the ratio of K.E. of electron and K.E. of photon will be: (1) 1 (2) 1 1 8 (3) 8 (4) 1 1 4

Q18.According to Bohr's theory, the moment of momentum of an electron revolving in 4th orbit of hydrogen atom is: (1) h (2) h π 2π (3) 8 hπ (4) 2 hπ JEE Main 2024 (04 Apr Shift 2) JEE Main Previous Year Paper

Q18.The longest wavelength associated with Paschen series is : (Given RH = 1.097 × 107SI unit) (1) 3.646 × 10−6 m (2) 1.876 × 10−6 m (3) 2.973 × 10−6 m (4) 1.094 × 10−6 m

Q18.Binding energy of a certain nucleus is 18 × 108 J. How much is the difference between total mass of all the nucleons and nuclear mass of the given nucleus: (1) 10μg (2) 20μg (3) 0.2μg (4) 2μg

Q18.The mass number of nucleus having radius equal to half of the radius of nucleus with mass number 192 is: (1) 24 (2) 32 (3) 40 (4) 20

Q18. Given below are two statements : Statement I : Figure shows the variation of stopping potential with frequency (v) for the two photosensitive materials M1 and M2 . The slope gives value of h , where h is Planck's constant, e is the charge of electron. Statement II : M2 will emit photoelectrons of e greater kinetic energy for the incident radiation having same frequency. In the light of the above statements, choose the most appropriate answer from the options given below. (1) Both Statement I and Statement II are correct (2) Statement I is incorrect but Statement II is correct (3) Both Statement I and Statement II are incorrect (4) Statement I is correct and Statement II is incorrect

Q18.The atomic mass of 6C12 is 12 . 000000 u and that of 6C13 is 13 . 003354 u. The required energy to remove a neutron from 6C13 , if mass of neutron is 1 . 008665 u, will be: (1) 62 . 5MeV (2) 6 . 25MeV (3) 4 . 95MeV (4) 49 . 5MeV

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