Practice Questions

Q29.Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A: Diffusion current in a p −n junction is greater than the drift current in magnitude if the junction is forward biased. Reason R: Diffusion current in a p −n junction is form the n-side to the p-side if the junction is forward biased. In the light of the above statements, choose the most appropriate answer from the options given below. (1) Both A and R are correct but R is NOT the (2) A is correct but R is not correct correct explanation of A (3) A is not correct but R is correct (4) Both A and R is correct and R is the correct explanation of A

Q29.A thin cylindrical rod of length 10 cm is placed horizontally on the principle axis of a concave mirror of focal length 20 cm. The rod is placed in a such a way that mid point of the rod is at 40 cm from the pole of mirror. The length of the image formed by the mirror will be 𝑥 cm. The value of 𝑥 is ______. 3

Q29.In a medium the speed of light wave decreases to 0 . 2 times to its speed in free space. The ratio of relative permittivity to the refractive index of the medium is 𝑥: 1. The value of 𝑥 is ______. (Given speed of light in free space = 3 × 108 m s-1 and for the given medium 𝜇𝑟= 1)

Q29.A point source of light is placed at the centre of curvature of a hemispherical surface. The source emits a power of 24 W. The radius of curvature of hemisphere is 10 cm and the inner surface is completely reflecting. The force on the hemisphere due to the light falling on it is ______ × 10-8 N.

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.The logic gate equivalent to the given circuit diagram is : JEE Main 2023 (24 Jan Shift 2) JEE Main Previous Year Paper (1) OR (2) NAND (3) NOR (4) AND

Q29.Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R Assertion A: Photodiodes are used in forward bias usually for measuring the light intensity. Reason R: For a p −n junction diode, at applied voltage V the current in the forward bias is more than the current in the reverse bias for |Vz| > ±V ≥|V0| where V0 is the threshold voltage and Vz is the breakdown voltage. In the light of the above statements, choose the correct answer from the options given below (1) Both A and R are true and R is correct (2) Both A and R are true but R is NOT the correct explanation A explanation A (3) A is false but R is true (4) A is true but R is false

Q29.The energy levels of an atom is shown is figure. Which one of these transitions will result in the emission of a photon of wavelength 124. 1 nm? Given ( h = 6. 62 × 10–34 J s) JEE Main 2023 (25 Jan Shift 2) JEE Main Previous Year Paper (1) B (2) A (3) C (4) D

Q29.From the given transfer characteristic of a transistor in CE configuration, the value of power gain of this configuration is 10x , for RB = 10 kΩ, and RC = 1 kΩ. The value of x is _____. JEE Main 2023 (13 Apr Shift 1) JEE Main Previous Year Paper

Q29.The output Y for the inputs A and B of circuit is given by Truth table of the shown circuit is : (1) A B Y (2) A B Y ⎡ 0 0 1 ⎤ ⎡ 0 0 1 ⎤ 0 1 1 0 1 0 1 0 1 1 0 0 1 1 0 1 1 1 ⎣ ⎦ ⎣ ⎦ (3) A B Y (4) A B Y ⎡ 0 0 0 ⎤ ⎡ 0 0 0 ⎤ 0 1 1 0 1 1 1 0 1 1 0 1 1 1 1 1 1 0 ⎣ ⎦ ⎣ ⎦

Q29.Given below are two statements: Statement I : In a typical transistor, all three regions emitter, base and collector have same doping level. Statement II : in a transistor, collector is the thickest and base is the thinnest segment. In the light of the above statements, choose the most appropriate answer from the options given below. (1) Both Statement I and Statement II are correct (2) Both Statement I and Statement II are incorrect (3) Statement I is incorrect but Statement II is (4) Statement I is correct but Statement II is correct incorrect

Q29.A bi convex lens of focal length 10 cm is cut in two identical parts along a plane perpendicular to the principal axis. The power of each lens after cut is _____ D.

Q29.Unpolarised light of intensity 32 W m−2 passes through the combination of three polaroids such that the pass axis of the last polaroids is perpendicular to that of the pass axis of first polaroids. If intensity of emerging light is 3 W m−2, then the angle between pass axis of first two polaroids is _________°.

Q29.For the logic circuit shown, the output waveform at Y is (1) (2) (3) (4)

Q29.For a given transistor amplifier circuit in CE configuration VCC = 1 V, RC = 1 kΩ, Rb = 100 kΩ and β = 100 . Value of base current Ib is JEE Main 2023 (08 Apr Shift 2) JEE Main Previous Year Paper (1) Ib = 1. 0 μA (2) Ib = 0. 1 μA (3) Ib = 100 μA (4) Ib = 10 μA

Q30.A TV transmitting antenna is 98 m high and the receiving antenna is at the ground level. If the radius of the earth is 6400 km, the surface area covered by the transmitting antenna is approximately: JEE Main 2023 (08 Apr Shift 1) JEE Main Previous Year Paper (1) 1240 km2 (2) 3942 km2 (3) 4868 km2 (4) 1549 km2 Q31. 0. 5 g of an organic compound (X) with 60% carbon will produce ×10−1 g of CO2 on complete combustion.

Q30.As per given figure A, B and C are the first, second and third excited energy levels of hydrogen atom n will be e. λ2 respectively. If the ratio of the two wavelengths (i. λ1 ) is 4n7 , then the value of

Q30.For hydrogen atom, 𝜆1 and 𝜆2 are the wavelengths corresponding to the transitions 1 and 2 respectively as 𝑥 shown in figure. The ratio of 𝜆1 and 𝜆2 is 32. The value of 𝑥 is ______.

Q30.A light of energy 12 . 75 eV is incident on a hydrogen atom in its ground state. The atom absorbs the radiation and reaches to one of its excited states. The angular momentum of the atom in the excited state is 𝑥 – 15 – 𝜋× 10-17 eVs. The value of 𝑥 is ______ (use ℎ= 4 . 14 × 10 eVs, 𝑐= 3 × 108 m s 1)

Q30.In a screw gauge, there are 100 divisions on the circular scale and the main scale moves by 0 . 5 mm on a complete rotation of the circular scale. The zero of circular scale lies 6 divisions below the line of graduation when two studs are brought in contact with each other. When a wire is placed between the studs, 4 linear scale divisions are clearly visible while 46th division the circular scale coincide with the reference line. The diameter of the wire is ______ × 10-2 mm .

Q30.Assume that protons and neutrons have equal masses. Mass of a nucleon is 1 . 6 × 10-27 kg and radius of 1 nucleus is 1 . 5 × 10-15 A 3 m. The approximate ratio of the nuclear density and water density is n × 1013. The value of n is _____.

Q30.The decay constant for a radioactive nuclide is 1 . 5 × 10-5 s-1. Atomic weight of the substance is 60 g mole-1, 𝑁𝐴= 6 × 1023. The activity of 1 . 0 µ g of the substance is ________ × 1010 Bq.

Q30.Statement I : When a Si sample is doped with Boron, it becomes P type and when doped by Arsenic it becomes N-type semi conductor such that P-type has excess holes and N-type has excess electrons. Statement II : When such P-type and N-type semi-conductors, are fused to make a junction, a current will automatically flow which can be detected with an externally connected ammeter. In the light of above statements, choose the most appropriate answer from the options given below. (1) Both Statement I and statement II are incorrect (2) Statement I is incorrect but statement II is correct (3) Both Statement I and statement II are correct (4) Statement I is correct but statement II is incorrect

Q30.Given below are two statements Statement I : For transmitting a signal, size of antenna (l) should be comparable to wavelength of signal (at least l = λ4 in dimension). Statement II : In amplitude modulation, amplitude of carrier wave remains constant (unchanged). In the light of the above statements, choose the most appropriate answer from the options given below JEE Main 2023 (31 Jan Shift 2) JEE Main Previous Year Paper (1) Both Statement I and Statement II are correct (2) Both Statement I and Statement II are incorrect (3) Statement I is incorrect but Statement II is (4) Statement I is correct but Statement II is correct incorrect