Practice Questions

Q16.If the distance between object and its two times magnified virtual image produced by a curved mirror is 15 cm , the focal length of the mirror must be : (1) 15 cm (2) −12 cm (3) −10 cm (4) 103 cm

Q16.In photoelectric experiment energy of 2.48eV irradiates a photo sensitive material. The stopping potential was measured to be 0.5 V. Work function of the photo sensitive material is : (1) 1.68eV (2) 2.48eV (3) 1.98eV (4) 0.5eV

Q16.A convex mirror of radius of curvature 30 cm forms an image that is half the size of the object. The object distance is : (1) −45 cm (2) 45 cm (3) −15 cm (4) 15 cm

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.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.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.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 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.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.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.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.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

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 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

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

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

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.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