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.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

Q17.The equation 𝜆= nm can be used to find the de-Broglie wavelength of an electron. In this equation 𝑥 x stands for : Where, 𝑚= mass of electron 𝑃= momentum of electron 𝐾= Kinetic energy of electron 𝑉= Accelerating potential in volts for electron (1) √𝑚𝐾 (2) √𝑃 (3) √𝐾 (4) √𝑉

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.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.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

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.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.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 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.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.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.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.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

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.Identify the logic operation performed by the given circuit (1) AND gate (2) OR gate (3) NOR gate (4) NAND gate

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.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 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.Hydrogen atom from excited state comes to the ground by emitting a photon of wavelength λ. The value of principal quantum number n of the excited state will be : ( R : Rydberg constant) (1) √λRλ−1 (2) √ λR−1λR (3) √ λR−1λ (4) √λR2λR−1

Q19.The photodiode is used to detect the optical signals. These diodes are preferably operated in reverse biased mode because (1) fractional change in majority carriers produce (2) fractional change in majority carriers produce higher forward bias current higher reverse bias current (3) fractional change in minority carriers produce (4) fractional change in minority carriers produce higher forward bias current higher reverse bias current

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)

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.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.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