Practice Questions

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.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.A plane electromagnetic wave travels in a medium of relative permeability 1. 61 and relative permittivity 6. 44 . If magnitude of magnetic intensity is 4. 5 × 10−2 A m−1 at a point, what will be the approximate magnitude of electric field intensity at that point ? (Given : Permeability of free space μ0 = 4π × 10−7 N A−2 , speed of light in vacuum c = 3 × 108 m s−1 ) (1) 16. 96 V m−1 (2) 2. 25 × 10−2 V m−1 (3) 8. 48 V m−1 (4) 6. 75 × 106 V m−1

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.The disintegration rate of a certain radioactive sample at any instant is 4250 disintegrations per minute. 10 minutes later, the rate becomes 2250 disintegrations per minute. The approximate decay constant is (Take loge 1. 88 = 0. 63 ) (1) 0. 02 min−1 (2) 2. 7 min−1 (3) 0. 063 min−1 (4) 6. 3 min−1

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.A metal exposed to light of wavelength 800 nm and emits photoelectrons with a certain kinetic energy. The maximum kinetic energy of photo-electron doubles when light of wavelength 500 nm is used. The work JEE Main 2022 (25 Jul Shift 1) JEE Main Previous Year Paper function of the metal is (Take ℎ𝑐= 1230 eV - nm). (1) 1 . 537eV (2) 2 . 46eV (3) 0 . 615eV (4) 1 . 23eV

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

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.A radioactive nucleus can decay by two different processes. Half-life for the first process is 3. 0 hours while it is 4. 5 hours for the second process. The effective halflife of the nucleus will be (1) 3. 75 hours (2) 0. 56 hours (3) 0. 26 hours (4) 1. 80 hours

Q18.The ratio of wavelengths of proton and deuteron accelerated by potential Vp and Vd is 1 : √2 . Then, the ratio of Vp to Vd will be (1) 1 : 1 (2) √2 : 1 (3) 2 : 1 (4) 4 : 1

Q18.Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : The photoelectric effect does not take place, if the energy of the incident radiation is less than the work function of a metal. Reason R : Kinetic energy of the photoelectrons is zero, if the energy of the incident radiation is equal to the work function of a metal. (1) Both A and R are correct and R is the correct (2) Both A and R are correct but R is not the correct explanation of A explanation of A (3) A is correct but R is not correct (4) A is not correct but R is correct

Q18.How many alpha and beta particles are emitted when Uranium 92U238 decays to lead 82 Pb206 ? (1) 3 alpha particles and 5 beta particles (2) 6 alpha particles and 4 beta particles (3) 4 alpha particles and 5 beta particles (4) 8 alpha particles and 6 beta particles

Q18.Following statements related to radioactivity are given below : (A) Radioactivity is a random and spontaneous process and is dependent on physical and chemical conditions. (B) The number of undecayed nuclei in the radioactive sample decays exponentially with time. (C) Slope of the graph of loge (no. of undecayed nuclei) vs. time represents the reciprocal of mean life time (τ) . 1 (D) Product of decay constant (λ) and half-life time (T 2 ) is not constant. Choose the most appropriate answer from the options given below: (1) (A) and (B) only (2) (B) and (D) only (3) (B) and (C) only (4) (C) and (D) only

Q19.The I −V characteristics of a p −n junction diode in forward bias is shown in the figure. The ratio of dynamic resistance, corresponding to forward bias voltage of 2 V and 4 V respective is (1) 1 : 2 (2) 5 : 1 (3) 1 : 40 (4) 20 : 1

Q19.An n.p.n transistor with current gain β = 100 in common emitter configuration is shown in figure. The output voltage of the amplifier will be (1) 0. 1 V (2) 1. 0 V (3) 10 V (4) 100 V

Q19.In the given circuit the input voltage Vin is shown in figure. The cut-in voltage of p −n junction diode ( D1 or D2 ) is 0. 6 V . Which of the following output voltage (V0) waveform across the diode is correct? JEE Main 2022 (28 Jun Shift 2) JEE Main Previous Year Paper (1) (2) (3) (4)

Q19.Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R. Assertion A : n −p −n transistor permits more current than a p −n −p transistor. Reason R : Electrons have greater mobility as a charge carrier. (1) Both A and R true, and R is correct explanation (2) Both A and R are true but R is NOT the correct of A. explanation of A. (3) A is true but R is false. (4) A is false but R is true.

Q19.A travelling microscope has 20 divisions per cm on the main scale while its Vernier scale has total 50 divisions and 25 Vernier scale divisions are equal to 24 main scale divisions, what is the least count of the travelling microscope ? (1) 0. 001 cm (2) 0. 002 mm (3) 0. 002 cm (4) 0. 005 cm

Q19.An 𝛼 particle and a proton are accelerated from rest through the same potential difference. The ratio of linear momenta acquired by above two particals will be : (1) √2: 1 (2) 2√2: 1 (3) 4√2: 1 (4) 8: 1

Q19.The activity of a radioactive material is 2. 56 × 10−3 Ci. If the half life of the material is 5 days, after how many days the activity will become 2 × 10−5 Ci? JEE Main 2022 (29 Jun Shift 1) JEE Main Previous Year Paper (1) 30 days (2) 35 days (3) 40 days (4) 25 days

Q19.In the following nuclear reaction, β− γ D α→D1 →D2 α→D3 →D4 Mass number of D is 182 and atomic number is 74 . Mass number and atomic number of D4 respectively will be (1) 174 and 71 (2) 174 and 69 (3) 172 and 69 (4) 172 and 71

Q19.The positive feedback is required by an amplifier to act as an oscillator. The feedback here means (1) External input is necessary to sustain ac signal in (2) A portion of the output power is returned back to output. the input. (3) Feedback can be achieved by LR network. (4) The base-collector junction must be forward biased.

Q19.A hydrogen atom in its ground state absorbs 10. 2 eV of energy. The angular momentum of electron of the hydrogen atom will increase by the value of (Given, Planck's constant = 6. 6 × 10−34 Js ). (1) 2. 10 × 10−34 Js (2) 1. 05 × 10−34 Js (3) 3. 15 × 10−34 Js (4) 4. 2 × 10−34 Js

Q19.Identify the solar cell characteristics from the following options : JEE Main 2022 (28 Jul Shift 1) JEE Main Previous Year Paper (1) (2) (3) (4)