Practice Questions

Q19.The light of two different frequencies whose photons have energies 3. 8 eV and 1. 4 eV respectively, illuminate a metallic surface whose work function is 0. 6 eV successively. The ratio of maximum speeds of emitted electrons for the two frequencies respectively will be : (1) 2 : 1 (2) 4 : 1 (3) 1 : 2 (4) 1 : 4

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

Q19.A radio can tune to any station in 6 MHz to 10 MHz band. The value of corresponding wavelength bandwidth will be (1) 4 m (2) 20 m (3) 30 m (4) 50 m

Q20.In a Vernier Caliper 10 divisions of Vernier scale is equal to the 9 divisions of main scale. When both jaws of Vernier calipers touch each other, the zero of the Vernier scale is shifted to the left of zero of the main scale and 4th Vernier scale division exactly coincides with the main scale reading. One main scale division is equal to 1 mm. While measuring diameter of a spherical body, the body is held between two jaws. It is now observed that zero of the Vernier scale lies between 30 and 31 divisions of main scale reading and 6th Vernier scale division exactly. coincides with the main scale reading. The diameter of the spherical body will be: (1) 3 . 02 cm (2) 3 . 06 cm (3) 3 . 10 cm (4) 3 . 20 cm

Q20.We do not transmit low frequency signal to long distances because (a) The size of the antenna should be comparable to signal wavelength which is unreal solution for a signal of longer wavelength. (b) Effective power radiated by a long wavelength baseband signal would be high. (c) We want to avoid mixing up signals transmitted by different transmitter simultaneously. (d) Low frequency signal can be sent to long distances by superimposing with a high frequency wave as well. Therefore, the most suitable option will be : (1) All statements are true (2) (a), (b) and (c) are true only (3) (a), (c) and (d) are true only (4) (b), (c) and (d) are true only

Q20.Only 2% of the optical source frequency is the available channel bandwidth for an optical communicating system operating at 1000 nm. If an audio signal requires a bandwidth of 8 kHz, how many channels can be accommodated for transmission (1) 375 × 107 (2) 75 × 107 (3) 375 × 108 (4) 75 × 109

Q20.In an experiment to find out the diameter of wire using screw gauge, the following observation were noted: (a) Screw moves 0. 5 mm on main scale in one complete rotation (b) Total divisions on circular scale = 50 (c) Main scale reading is 2. 5 mm (d) 45th division of circular scale is in the pitch line (e) Instrument has 0. 03 mm negative error Then the diameter of wire is : (1) 2. 92 mm (2) 2. 54 mm (3) 2. 98 mm (4) 3. 45 mm

Q20.Read the following statements: (A) Volume of the nucleus is directly proportional to the mass number. (B) Volume of the nucleus is independent of mass number. (C) Density of the nucleus is directly proportional to the mass number. (D) Density of the nucleus is directly proportional to the cube root of the mass number. (E) Density of the nucleus is independent of the mass number. Choose the correct option from the following options. (1) (A) and (D) only. (2) (A) and (E) only. (3) (B) and (E) only. (4) (A) and (C) only

Q20.In the circuit, the logical value of 𝐴= 1 or 𝐵= 1 when potential at 𝐴 or 𝐵 is 5 V and the logical value of 𝐴= 0 or 𝐵= 0 when potential at 𝐴 or 𝐵 is 0V. The truth table of the given circuit will be : (1) 𝐴 𝐵𝑌 (2) 𝐴 𝐵𝑌 0 0 0 0 0 0 1 0 0 1 0 1 0 1 0 0 1 1 1 1 1 1 1 1 (3) 𝐴 𝐵𝑌 (4) 𝐴 𝐵𝑌 0 0 0 0 0 1 1 0 0 1 0 1 0 1 0 0 1 1 1 1 0 1 1 0

Q20.Match List I with List II List I List II (A) Facsimile (I) Static Document Image (B) Guided media Channel (II) Local Broadcast Radio (C) Frequency Modulation (III) Rectangular wave (D) Digital Signal (IV) Optical Fiber Choose the correct answer from the following options (1) A - IV, B - III, C - II, D - I (2) A - I, B - IV, C - II, D - III (3) A - IV, B - II, C - III, D - I (4) A - I, B - II, C - III, D - IV

Q20.A baseband signal of 3. 5 MHz frequency is modulated with a carrier signal of 3. 5 GHz frequency using amplitude modulation method. What should be the minimum size of antenna required to transmit the modulated signal ? (1) 42. 8 m (2) 42. 8 mm (3) 21. 4 mm (4) 21. 4 m

Q20.In Bohr's atomic model of hydrogen, let K, P and E are the kinetic energy, potential energy and total energy of the electron respectively. Choose the correct option when the electron undergoes transitions to a higher level : (1) All K, P and E increase. (2) K decreases, P and E increase. (3) P decreases, K and E increase. (4) K increases, P and E decrease

Q20.A sinusoidal wave y(t) = 40 sin(10 × 106πt) is amplitude modulated by another sinusoidal wave x(t) = 20 sin(1000πt). The amplitude of minimum frequency component of modulated signal is (1) 0. 5 (2) 0. 25 (3) 20 (4) 10

Q21.The moment of inertia of a uniform thin rod about a perpendicular axis passing through one end is I1 . The x same rod is bent into a ring and its moment of inertia about a diameter is I2 . If I2I1 is xπ23 , then the value of will be ______.

Q21.A body is projected from the ground at an angle of 45° with the horizontal. Its velocity after 2 s is 20 m s−1 . The maximum height reached by the body during its motion is _____ m . (use g = 10 m s−2 )

Q21.A tube of length 50 cm is filled completely with an incompressible liquid of mass 250 g and closed at both ends. The tube is then rotated in horizontal plane about one of its ends with a uniform angular velocity 𝑥√𝐹 rad s-1. If 𝐹 be the force exerted by the liquid at the other end then the value of 𝑥 will be _____ .

Q21.In an experiment to find acceleration due to gravity (g) using simple pendulum, time period of 0. 5 s is measured from time of 100 oscillation with a watch of 1 s resolution. If measured value of length is 10 cm known to 1 mm accuracy. The accuracy in the determination of g is found to be x%. The value of x is

Q21.A mass of 10 kg is suspended vertically by a rope of length 5 m from the roof. A force of 30 N is applied at the middle point of rope in horizontal direction. The angle made by upper half of the rope with vertical is α = tan−1(x × 10−1). The value of x is _____ . (Given, g = 10 m s−2 ) JEE Main 2022 (27 Jun Shift 2) JEE Main Previous Year Paper

Q21.As per the given figure, two plates A and B of thermal conductivity K and 2K are joined together to form a compound plate. The thickness of plates are 4. 0 cm and 2. 5 cm respectively and the area of cross-section is 120 cm2 for each plate. The equivalent thermal conductivity of the compound plate is (1 + α5 )K , then the value of α will be _____ . Q22. 300 calories of heat is given to a heat engine, and it rejects 225 calories of heat. If source temperature is 227°C, then the temperature of sink will be _____ ∘C.

Q21.Two inclined planes are placed as shown in figure. A block is projected from the Point A of inclined plane AB along its surface with a velocity just sufficient to carry it to the top Point B at a height 10 m. After reaching the Point B the block slides down on inclined plane + BC . Time it takes to reach to the point C from point A is t(√2 1)s. The value of t is _____ (use g = 10 m s−2 )

Q21.A particle is moving in a straight line such that its velocity is increasing at 5 m s−1 per meter. The acceleration of the particle is _____ m s−2 at a point where its velocity is 20 m s−1 .

Q21.A uniform chain of 6 m length is placed on a table such that a part of its length is hanging over the edge of the table. The system is at rest. The co-efficient of static friction between the chain and the surface of the table is 0 . 5, the maximum length of the chain hanging from the table is _____ m.

Q21.A ball is projected vertically upward with an initial velocity of 50 m s−1 at t = 0 s. At t = 2 s, another ball is projected vertically upward with same velocity. At t =____ s, second ball will meet the first ball (g = 10 m s−2) .