Practice Questions

Q28.Given below are two statements : Statement I : Stopping potential in photoelectric effect does not depend on the power of the light source. Statement II : For a given metal, the maximum kinetic energy of the photoelectron depends on the wavelength of the incident light. In the light of above statements, choose the most appropriate answer from the options given below. (1) Statement I is incorrect but statement II is correct (2) Both Statement I and Statement II are incorrect (3) Statement I is correct but statement II is incorrect (4) Both statement I and statement II are correct

Q28.Which of the following statement is not correct in the case of light emitting diodes? A. It is a heavily doped p-n junction. B. It emits light only when it is forward biased. C. It emits light only when it is reverse biased. D. The energy of the light emitted is equal to or slightly less than the energy gap of the semiconductor used. Choose the correct answer from the options given below : (1) C and D (2) A (3) C (4) B

Q28.In the circuit shown in the figure, the ratio of the quality factor and the band width is _____ s.

Q28.An ideal transformer with purely resistive load operates at 12 kV on the primary side. It supplies electrical energy to a number of nearby houses at 120 V . The average rate of energy consumption in the houses served by the transformer is 60 kW . The value of resistive load ( 𝑅𝑠) required in the secondary circuit will be _________mΩ .

Q28.A 20 cm long metallic rod is rotated with 210 rpm about an axis normal to the rod passing through its one end. The other end of the rod is in contact with a circular metallic ring. A constant and uniform magnetic field 0. 2 T parallel to the axis exists everywhere. The emf developed between the centre and the ring is _________ mV. JEE Main 2023 (15 Apr Shift 1) JEE Main Previous Year Paper (Take π = 227 )

Q28.A series LCR circuit is connected to an ac source of 220 V, 50 Hz. The circuit contain a resistance 𝑅= 100 Ω and an inductor of inductive reactance 𝑋𝐿= 79 . 6 Ω. The capacitance of the capacitor needed to maximize the average rate at which energy is supplied will be ______ μF.

Q28.Nucleus a having Z = 17 and equal number of protons and neutrons has 1. 2 MeV binding energy per nucleon. Another nucleus B of Z = 12 has total 26 nucleons and 1. 8 MeV binding energy per nucleons. The JEE Main 2023 (01 Feb Shift 2) JEE Main Previous Year Paper difference of binding energy of B and A will be ______ MeV.

Q28.In Young’s double slit experiment, two slits 𝑆1 and 𝑆2 are 𝑑 distance apart and the separation from slits to screen is 𝐷 (as shown in figure). Now if two transparent slabs of equal thickness 0 . 1 mm but refractive index 1 . 51 and 1 . 55 are introduced in the path of beam λ = 4000 Å from 𝑆1 and 𝑆2 respectively. The central bright fringe spot will shift by ________ number of fringes.

Q28.An inductor of 0 . 5 mH, a capacitor of 20 μF and resistance of 20 Ω are connected in series with a 220 V ac source. If the current is in phase with the emf, the amplitude of current of the circuit is √𝑥 A. The value of 𝑥 is-

Q28.A square loop of side 2 . 0 cm is placed inside a long solenoid that has 50 turns per centimetre and carries a sinusoidally varying current of amplitude 2 . 5 A and angular frequency 700 rad s-1. The central axes of the loop and solenoid coincide. The amplitude of the emf induced in the loop is 𝑥× 10-4 V. The value of 𝑥 is ___________ ( Take, 𝜋= 22 7

Q28.A radio active material is reduced to 1 of its original amount in 3 days. If 8 × 10−3 kg of the material is left 8 after 5 days the initial amount of the material is (1) 40 g (2) 32 g (3) 64 g (4) 256 g

Q28.The energy released per fission of nucleus of 240X is 200 MeV . The energy released if all the atoms in 120 g of pure 240X undergo fission is _____ ×1025 MeV . (Given NA = 6 × 1023 )

Q28.If the binding energy of ground state electron in a hydrogen atom is 13. 6 eV , then, the energy required to remove the electron from the second excited state of Li 2+ will be: x × 10−1 eV . The value of x is _____.

Q28.For the following circuit and given inputs A and B, choose the correct option for output ‵Y ′ JEE Main 2023 (13 Apr Shift 1) JEE Main Previous Year Paper (1) (2) (3) (4)

Q28.A common example of alpha decay is 23892U →23490 Th +2 He4 + Q Given: 23892U = 238. 05060 u 23490Th = 234. 04360 u 42He = 4. 00260 u and 1u = 931. 5 MeVc2 The energy released (Q) during the alpha decay of 23892U is _____ MeV.

Q28.An insulated copper wire of 100 turns is wrapped around a wooden cylindrical core of the cross-sectional area 24 cm2. The two ends of the wire are connected to a resistor. The total resistance in the circuit is 12 Ω. If an externally applied uniform magnetic field in the core along its axis changes from 1 . 5 T in one direction to 1 . 5 T in the opposite direction, the charge flowing through a point in the circuit during the change of magnetic field will be _____ mC.

Q28.The work functions of Aluminium and Gold are 4. 1 eV and 5. 1 eV respectively. The ratio of the slope of the stopping potential versus frequency plot for Gold to that of Aluminium is (1) 1. 24 (2) 2 (3) 1 (4) 1. 5

Q28.The ratio of the density of oxygen nucleus (168O) and helium nucleus (42He) is (1) 4 : 1 (2) 8 : 1 (3) 1 : 1 (4) 2 : 1

Q28.The energy of He+ ion in its first state is, (The ground state energy for the Hydrogen atom −13. 6 eV): (1) −27. 2 eV (2) −3. 4 eV (3) −13. 6 eV (4) −54. 4 eV

Q28.For the given logic gates combination, the correct truth table will be (1) A B X (2) A B X 0 0 1 0 0 0 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 0 (3) A B X (4) A B X 0 0 1 0 0 0 0 1 0 0 1 1 1 0 1 1 0 1 1 1 0 1 1 1

Q28.A nucleus with mass number 242 and binding energy per nucleon as 7. 6 MeV breaks into two fragment each with mass number 121. If each fragment nucleus has binding energy per nucleon as 8. 1 MeV, the total gain in binding energy is _______ MeV.

Q28.A radioactive nucleus decays by two different process. The half life of the first process is 5 minutes and that of the second process is 30 s. The effective half-life of the nucleus is calculated to be 11α s. The value of α is ______.

Q29.The refractive index of a transparent liquid filled in an equilateral hollow prism is √2. The angle of minimum deviation for the liquid will be _______ °.

Q29.The radius of curvature of each surface of a convex lens having refractive index 1 . 8 is 20 cm. The lens is now immersed in a liquid of refractive index 1 . 5. The ratio of power of lens in air to its power in the liquid will be 𝑥: 1. The value of 𝑥 is

Q29.If the height of transmitting and receiving antennas are 80 m each, the maximum line of sight distance will be : Given : Earth’s radius = 6. 4 × 106 m . (1) 32 km (2) 28 km (3) 36 km (4) 64 km