Practice Questions

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.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.In the following circuit, the correct relation between output (Y ) and inputs A and B will be JEE Main 2022 (28 Jun Shift 1) JEE Main Previous Year Paper (1) Y = A ⋅B (2) Y = A + B (3) Y = A ⋅B (4) Y = A + B

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.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

Q18.The activity of a radioactive material is 6. 4 × 10−4 curie. Its half life is 5 days. The activity will become 5 × 10−6 curie after (1) 7 days (2) 15 days (3) 25 days (4) 35 days JEE Main 2022 (27 Jul Shift 2) JEE Main Previous Year Paper

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.Given below are two statements Statement I: In hydrogen atom, the frequency of radiation emitted when an electron jumps from lower energy orbit (E1) to higher energy orbit (E2), is given as hf = E1 −E2 Statement II: The jumping of electron from higher energy orbit (E2) to lower energy orbit (E1) is associated with frequency of radiation given as f = (E2−E1)h . This condition is Bohr's frequency condition. 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 correct but statement II is false. (4) Statement I is incorrect but statement II is true.

Q18.Which of the following figure represents the variation of ln with ln𝐴 (if 𝑅= radius of a nucleus and 𝐴= 𝑅0 its mass number) JEE Main 2022 (25 Jun Shift 2) JEE Main Previous Year Paper (1) (2) (3) (4)

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.For using a multimeter to identify diode from electrical components, choose the correct statement out of the following about the diode (1) It is two terminal device which conducts current (2) It is two terminal device which conducts current in both directions. in one direction only (3) It does not conduct current gives an initial (4) It is three terminal device which conducts current deflection which decays to zero. in one direction only between central terminal and either of the remaining two terminals

Q18.An unpolarised light beam of intensity 2𝐼0 is passed through a polaroid 𝑃 and then through another polaroid 𝑄 which is oriented in such a way that its passing axis makes an angle of 30° relative to that of 𝑃. The intensity of the emergent light is (1) 𝐼0 (2) 𝐼0 4 2 3𝐼0 3𝐼0 (3) (4) 4 2 JEE Main 2022 (29 Jul Shift 2) 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.The ratio for the speed of the electron in the 3rd orbit of He+ to the speed of the electron in the 3rd orbit of hydrogen atom will be : (1) 1: 1 (2) 1: 2 (3) 4: 1 (4) 2: 1

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.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

Q19.The momentum of an electron revolving in 𝑛𝑡ℎ orbit is given by : (Symbols have their usual meanings) (1) 𝑛ℎ (2) 𝑛ℎ 2𝜋𝑟 2𝑟 𝑛ℎ 2𝜋𝑟 (3) (4) 2𝜋 𝑛ℎ

Q19.For a transistor to act as a switch, it must be operated in (1) Active region (2) Saturation and cut-off region (3) Cutoff region only (4) Saturated region only

Q19.A logic gate circuit has two inputs A and B and output Y . The voltage waveforms of A, B and Y are shown below The logic gate circuit is (1) AND gate (2) OR gate (3) NOR gate (4) NAND gate

Q19.For a constant collector-emitter voltage of 8 V , the collector current of a transistor reached to the value of 6 mA from 4 mA , whereas base current changed from 20 μA to 25 μA value. If transistor is in active state, small signal current gain (current amplification factor) will be (1) 240 (2) 400 (3) 0. 0025 (4) 200

Q19.The maximum and minimum voltage of an amplitude modulated signal are 60 V and 20 V respectively. The percentage modulation index will be (1) 0 . 5% (2) 50% (3) 2% (4) 30% JEE Main 2022 (26 Jul Shift 2) JEE Main Previous Year Paper

Q19.Nucleus A is having mass number 220 and its binding energy per nucleon is 5. 6 MeV . It splits in two fragments B and C of mass numbers 105 and 115 . The binding energy of nucleons in B and C is 6. 4 MeV per nucleon. The energy Q released per fission will be: (1) 0. 8 MeV (2) 275 MeV (3) 220 MeV (4) 176 MeV

Q20.In the case of amplitude modulation to avoid distortion the modulation index 𝜇 should be : (1) 𝜇≤1 (2) 𝜇≥1 (3) 𝜇= 2 (4) 𝜇= 0

Q20.A square wave of the modulating signal is shown in the figure. The carrier wave is given by C(t) = 5 sin(8πt) Volt. The modulation index is (1) 0. 2 (2) 0. 1 (3) 0. 3 (4) 0. 4

Q20.In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitude are found to be 6 V and 2 V respectively. The modulation index is (1) 100% (2) 80% (3) 60% (4) 50%