Practice Questions

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

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.A pole is vertically submerged in swimming pool, such that it gives a length of shadow 2 . 15 m within water when sunlight is incident at an angle of 30° with the surface of water. If swimming pool is filled to a height of ) ________ . 1 . 5 m, then the height of the pole above the water surface in centimeters is (𝑛𝑤= 43 ∘

Q29.As shown in the figure, a combination of a thin plano-concave lens and a thin plano-convex lens is used to image an object placed at infinity. The radius of curvature of both the lenses is 30 cm and refraction index of the material for both the lenses is 1 . 75. Both the lenses are placed at distance of 40 cm from each other. Due to the combination, the image of the object is formed at distance x = ______ cm, from concave lens.

Q29.The logic operations performed by the given digital circuit is equivalent to: (1) NOR (2) AND (3) OR (4) NAND

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.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.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.Choose the correct statement about Zener diode: (1) It works as a voltage regulator in reverse bias and (2) It works as a voltage regulator in both forward behaves like simple p-n junction diode in forward and reverse bias bias (3) It works a voltage regulator only in forward bias (4) It works as a voltage regulator in forward bias and behaves like simple p-n junction diode in reverse bias

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

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.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

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.A point object 𝑂 is placed in front of two thin symmetrical coaxial convex lenses 𝐿1 and 𝐿2 with focal length 24 cm and 9 cm respectively. The distance between two lenses is 10 cm and the object is placed 6 cm away from lens 𝐿1 as shown in the figure. The distance between the object and the image formed by the system of two lenses is _____________ cm

Q29.The modulation index for an A.M. wave having maximum and minimum peak to peak voltages of 14 mV and 6 mV respectively is : (1) 1. 4 (2) 0. 4 (3) 0. 2 (4) 0. 6

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 ⎣ ⎦ ⎣ ⎦

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.If 917 Å be the lowest wavelength of Lyman series then the lowest wavelength of Balmer series will be Å.

Q30.In a metre bridge experiment the balance point is obtained if the gaps are closed by 2 Ω and 3 Ω. A shunt of X Ω is added to 3 Ω resistor to shift the balancing point by 22. 5 cm. The value of X is ______.

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.