Practice Questions

Q17.Time taken by light to travel in two different materials 𝐴 and 𝐵 of refractive indices 𝜇𝐴 and 𝜇𝐵 of same thickness is 𝑡1 and 𝑡2 respectively. If 𝑡2 - 𝑡1 = 5 × 10-10s and the ratio of 𝜇𝐴 to 𝜇𝐵 is 1: 2. Then the thickness of material, in meter is: (Given 𝑣𝐴 and 𝑣𝐵 are velocities of light in 𝐴 and 𝐵 materials respectively). (1) 5 × 10-10𝑣𝐴 m (2) 5 × 10-10 m (3) 1 . 5 × 1010 m (4) 5 × 10-10𝑣𝐵 m

Q17.Which is the correct ascending order of wavelengths? (1) λvisible < λX−ray < λgamma−ray < λmicrowave (2) λgamma−ray < λX−ray < λvisible < λmicrowave (3) λX−ray < λgamma−ray < λvisible < λmicrowave (4) λmicrowave < λvisible < λgamma−ray < λX−ray

Q17.A proton, a neutron, an electron and an 𝛼-particle have same energy. If 𝜆𝑝, 𝜆𝑛, 𝜆𝑒 and 𝜆𝛼 are the de Broglie's wavelengths of proton, neutron, electron and 𝛼 particle respectively, then choose the correct relation from the following (1) 𝜆𝑝= 𝜆𝑛> 𝜆𝑒> 𝜆𝛼 (2) 𝜆𝑎< 𝜆𝑛< 𝜆𝑝< 𝜆𝑒 (3) 𝜆𝑒< 𝜆𝑝= 𝜆𝑛> 𝜆𝛼 (4) 𝜆𝑒= 𝜆𝑝= 𝜆𝑛= 𝜆𝛼. 𝑅

Q17.Given below are two statements : Statement I : Davisson-Germer experiment establishes the wave nature of electrons. Statement II : If electrons have wave nature, they can interfere and show diffraction. In the light of the above statements choose the correct answer from the option given below : (1) Both Statement I and Statement II are true. (2) Both Statement I and Statement II are false. (3) Statement I is true but Statement II is false. (4) Statement I is false but Statement II is true.

Q17.Light enters from air into a given medium at an angle of 45° with interface of the air-medium surface. After refraction, the light ray is deviated through an angle of 15° from its original direction. The refractive index of the medium is : (1) 1 . 732 (2) 1 . 333 (3) 1 . 414 (4) 2 . 732

Q17.Two streams of photons, possessing energies to five and ten times the work function of metal are incident on the metal surface successively. The ratio of the maximum velocities of the photoelectron emitted, in the two cases respectively, will be (1) 1 : 2 (2) 1 : 3 (3) 2 : 3 (4) 3 : 2

Q17.An electron with speed v and a photon with speed c have the same de-Broglie wavelength. If the kinetic energy and momentum of electron are Ee and Pe and that of photon are Eph and Pph respectively. Which of the JEE Main 2022 (26 Jun Shift 1) JEE Main Previous Year Paper following is correct? (1) Eph Ee = 2cv (2) EphEe = 2cv (3) pph pe = 2cv (4) pphpe = 2cv

Q17.For an object placed at a distance 2. 4 m from a lens, a sharp focused image is observed on a screen placed at a distance 12 cm from the lens. A glass plate of refractive index 1. 5 and thickness 1 cm is introduced between lens and screen such that the glass plate plane faces parallel to the screen. By what distance should the object be shifted so that a sharp focused image is observed again on the screen? (1) 0. 8 m (2) 3. 2 m (3) 1. 2 m (4) 5. 6 m

Q17.With reference to the observations in photo-electric effect, identify the correct statements from below: A. The square of maximum velocity of photoelectrons varies linearly with frequency of incident light. B. The value of saturation current increases on moving the source of light away from the metal surface. C. The maximum kinetic energy of photo-electrons decreases on decreasing the power of LED (light emitting diode) source of light. D. The immediate emission of photo-electrons out of metal surface can not be explained by particle nature of light/electromagnetic waves. E. Existence of threshold wavelength can not be explained by wave nature of light/electromagnetic waves. Choose the correct answer from the options given below: (1) A and B only (2) A and E only (3) C and E only (4) D and E only

Q17.A convex lens has power P . It is cut into two halves along its principal axis. Further one piece (out of the two halves) is cut into two halves perpendicular to the principal axis (as shown in figures). Choose the incorrect option for the reported pieces. (1) Power of L1 = P2 (2) Power of L2 = P2 (3) Power of L3 = P2 (4) Power of L1 = P

Q17.A parallel beam of light of wavelength 900 nm and intensity 100 Wm−2 is incident on a surface perpendicular to the beam. The number of photons crossing 1 cm2 area perpendicular to the beam in one second is (1) 3 × 1016 (2) 4. 5 × 1016 (3) 4. 5 × 1017 (4) 4. 5 × 1020

Q17.Let K1 and K2 be the maximum kinetic energies of photo-electrons emitted when two monochromatic beams of wavelength λ1 and λ2 , respectively are incident on a metallic surface. If λ1 = 3λ2 then : (1) K1 > K23 (2) K1 < K23 (3) K1 = K23 (4) K2 = K13

Q17.Consider a light ray travelling in air is incident into a medium of refractive index √2n. The incident angle is twice that of refracting angle. Then, the angle of incidence will be (1) sin−1 √n (2) cos−1( √2n ) (3) sin−1(√2n) (4) 2 cos−1(√n2 )

Q17.A nucleus of mass 𝑀 at rest splits into two parts having masses 𝑀' and 2𝑀' 𝑀' < 𝑀. The ratio of de Broglie 3 3 wavelength of two parts will be (1) 1: 2 (2) 2: 1 (3) 1: 1 (4) 2: 3

Q17.Given below are two statements : Statement-I: The reactance of an ac circuit is zero. It is possible that the circuit contains a capacitor and an inductor. JEE Main 2022 (24 Jun Shift 2) JEE Main Previous Year Paper Statement-II: In ac circuit, the average power delivered by the source never becomes zero. In the light of the above statements, choose the correct answer from the options given below (1) Both Statement I and Statement II are true. (2) Both Statement I and Statement II are false. (3) Statement I is true but Statement II is false. (4) Statement I is false but Statement II is true.

Q17.Using Young's double slit experiment, a monochromatic light of wavelength 5000Å produces fringes of fringe width 0. 5 mm. If another monochromatic light of wavelength 6000Å is used and the separation between the slits is doubled, then the new fringe width will be (1) 0. 5 mm (2) 1. 0 mm (3) 0. 6 mm (4) 0. 3 mm

Q18.Find the modulation index of an AM wave having 8 V variation where maximum amplitude of the AM wave is 9 V . (1) 0. 8 (2) 0. 5 (3) 0. 2 (4) 0. 1 JEE Main 2022 (29 Jul Shift 1) JEE Main Previous Year Paper

Q18.What is the half-life period of a radioactive material if its activity drops to 1 of its initial value of 30 years ? 16th (1) 9. 5 years (2) 8. 5 years (3) 7. 5 years (4) 10. 5 years JEE Main 2022 (27 Jul Shift 1) JEE Main Previous Year Paper

Q18.A radioactive sample decays 7 times its original quantity in 15 minutes. The half-life of the sample is 8 (1) 5 min (2) 7. 5 min (3) 15 min (4) 30 min

Q18.Choose the correct option from the following options given below : (1) In the ground state of Rutherford's model (2) An atom has a nearly continuous mass electrons are in stable equilibrium. While in distribution in a Rutherford's model but has a Thomson's model electrons always experience a highly non-uniform mass distribution in net-force. Thomson's model (3) A classical atom based on Rutherford's model is (4) The positively charged part of the atom possesses doomed to collapse. most of the mass in Rutherford's model but not in Thomson's model.

Q18.The half life period of a radioactive substance is 60 days. The time taken for 7 th of its original mass to 8 disintegrate will be : (1) 120 days (2) 130 days (3) 180 days (4) 20 days

Q18.The electric field at a point associated with a light wave is given by E = 200[sin(6 × 1015)t + sin(9 × 1015)t] Vm−1 Given: h = 4. 14 × 10−15 eVs If this light falls on a metal surface having a work function of 2. 50 eV , the maximum kinetic energy of the photoelectrons will be (1) 1. 90 eV (2) 3. 27 eV (3) 3. 60 eV (4) 3. 42 eV

Q18.Mass numbers of two nuclei are in the ratio of 4: 3. Their nuclear densities will be in the ratio of (1) 4: 3 (2) 3 13 4 (3) 1: 1 (4) 4 13 3

Q18.An α particle and a carbon 12 atom has same kinetic energy K . The ratio of their de-Broglie wavelengths (λα : λC12) is (1) √3 : 1 (2) 1 : √3 (3) 2 : √3 (4) 3 : 1

Q18.An electric bulb is rated as 200 W. What will be the peak magnetic field at 4 m distance produced by the radiations coming from this bulb? Consider this bulb as a point source with 3. 5% efficiency. (1) 1. 19 × 10−8T (2) 1. 71 × 10−8T (3) 0. 84 × 10−8T (4) 3. 36 × 10−8T