Practice Questions

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

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.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.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.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.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.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.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.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.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

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.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 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.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.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 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.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.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 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.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.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 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.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