Practice Questions

Q17.A particle is travelling 4 times as fast as an electron. Assuming the ratio of de-Broglie wavelength of a particle to that of electron is 2 : 1, the mass of the particle is :- (1) 1 times the mass of e− (2) 8 times the mass of e− 16 (3) 16 times the mass of e− (4) 18 times the mass of e−

Q17.The light waves from two coherent sources have same intensity I1 = I2 = I0. In interference pattern the intensity of light at minima is zero. What will be the intensity of light at maxima? (1) I0 (2) 2I0 (3) 4I0 (4) 5I0

Q17.For an electromagnetic wave travelling in free space, the relation between average energy densities due to electric (Ue) and magnetic (Um) fields is : (1) Ue = Um (2) Ue > Um (3) Ue < Um (4) Ue ≠Um

Q18.The atomic hydrogen emits a line spectrum consisting of various series. Which series of hydrogen atomic spectra is lying in the visible region? (1) Brackett series (2) Paschen series (3) Lyman series (4) Balmer series

Q18.The angle of deviation through a prism is minimum when (A) Incident ray and emergent ray are symmetric to the prism (B) The refracted ray inside the prism becomes parallel to its base (C) Angle of incidence is equal to that of the angle of emergence (D) When angle of emergence is double the angle of incidence Choose the correct answer from the options given below : (1) Statements (A),(B) and (C) are true (2) Only statement (D) is true (3) Only statements (A) and (B) are true (4) Statements (B) and (C) are true

Q18.In a Young's double slit experiment two slits are separated by 2 mm and the screen is placed one meter away. When a light of wavelength 500 nm is used, the fringe separation will be : (1) 1 mm (2) 0. 50 mm (3) 0. 75 mm (4) 0. 25 mm

Q18.In an electromagnetic wave, the electric field vector and magnetic field vector are given as E = E0ˆi and → B = B0ˆk, respectively. The direction of propagation of electromagnetic wave is along: (1) (ˆk) (2) ˆJ (3) (−ˆk) (4) (−ˆj)

Q18.In Young's double slit experiment, if the source of light changes from orange to blue then: (1) the central bright fringe will become a dark (2) the distance between consecutive fringes will fringe. decrease. (3) the distance between consecutive fringes will (4) the intensity of the minima will increase. increase.

Q18.In a photoelectric experiment, increasing the intensity of incident light: (1) increases the number of photons incident and also (2) increases the frequency of photons incident and increases the K.E. of the ejected electrons. increases the K.E. of the ejected electrons. (3) increases the number of photons incident and the (4) increases the frequency of photons incident and K.E. of the ejected electrons remains unchanged. the K.E. of the ejected electrons remains unchanged.

Q19.The following logic gate is equivalent to : (1) NOR Gate (2) OR Gate (3) AND Gate (4) NAND Gate

Q19.Which one of the following will be the output of the given circuit? (1) NOR Gate (2) NAND Gate (3) AND Gate (4) XOR Gate

Q19.Identify the logic operation carried out. (1) OR (2) AND (3) NOR (4) NAND

Q19.For a transistor α and β are given as α = IC and β = IC . Then the correct relation between α and β will be: IE IB (1) α = 1−ββ (2) αβ = 1 (3) β = 1−αα (4) α = 1−ββ

Q19.Zener breakdown occurs in a p −n junction having pand n both: (1) lightly doped and have narrow depletion layer. (2) heavily doped and have wide depletion layer. (3) lightly doped and have wide depletion layer. (4) heavily doped and have narrow depletion layer.

Q19.The stopping potential in the context of photoelectric effect depends on the following property of incident electromagnetic radiation: (1) Phase (2) Intensity (3) Amplitude (4) Frequency

Q19.If 𝑉𝐴 and 𝑉𝐵 are the input voltages (either 5 V or 0 V) and V0 is the output voltage then the two gates represented in the following circuits 𝐴 and 𝐵 are : (1) OR and NOT Gate (2) AND and NOT Gate (3) AND and OR Gate (4) NAND and NOR Gate

Q20.The correct relation between α (ratio of collector current to emitter current) and β (ratio of collector current to base current) of a transistor is : (1) β = 1+αα (2) α = 1−αβ (3) β = 1−α1 (4) α = 1+ββ JEE Main 2021 (18 Mar Shift 2) JEE Main Previous Year Paper

Q20.A transmitting antenna at top of a tower has a height of 50 m, and the height of receiving antenna is, 80 m. What is the range of communication for the line of sight (LOS) mode? [use radius of the earth = 6400 km] JEE Main 2021 (26 Aug Shift 2) JEE Main Previous Year Paper (1) 80. 2 km (2) 144. 1 km (3) 57. 28 km (4) 45. 5 km

Q20.In amplitude modulation, the message signal 𝑉m ( 𝑡) = 10sin2𝜋× 105𝑡 volts and carrier signal 𝑉C𝑡= 20sin2𝜋× 107𝑡 volts. The modulated signal now contains the message signal with lower side band and upper side band frequency, therefore the bandwidth of modulated signal is 𝛼 kHz. The value of 𝛼 is: (1) 200 kHz (2) 500 kHz (3) 100 kHz (4) 0

Q20.LED is constructed from Ga −As −P semiconducting material. The energy gap of this LED is 1. 9 eV . Calculate the wavelength of light emitted and its colour. h = 6. 63 × 10−34 J −s and c = 3 × 108 m s−1 (1) 654 nm and red colour (2) 654 nm and orange colour (3) 1046 nm and red colour (4) 1046 nm and blue colour → +

Q20.For a transistor in CE mode to be used as an amplifier, it must be operated in: (1) Cut-off region only (2) Saturation region only (3) The active region only (4) Both cut-off and Saturation

Q20.In the following logic circuit the sequence of the inputs A, B are (0, 0), (0, 1), (1, 0) and (1, 1). The output Y for this sequence will be : (1) 0, 1, 0, 1 (2) 0, 0, 1, 1 (3) 1, 1, 1, 0 (4) 1, 0, 1, 0

Q20.Find the truth table for the function Y of A and B represented in the following figure. (1) A B Y (2) A B Y 0 0 0 0 0 1 0 1 1 0 1 0 1 0 0 1 0 1 1 1 0 1 1 1 (3) A B Y (4) A B Y 0 0 0 0 0 0 0 1 0 0 1 1 1 0 0 1 0 1 1 1 1 1 1 1

Q20.If a message signal of frequency fm is amplitude modulated with a carrier signal of frequency fc and radiated through an antenna, the wavelength of the corresponding signal in air is (1) c (2) c fc−fm fm (3) c (4) c fc fc+fm → → → → → →

Q21.The coefficient of static friction between a wooden block of mass 0 . 5 kg and a vertical rough wall is 0 . 2 . The magnitude of the horizontal force that should be applied on the block to keep it adhere to the wall will be______N. 𝑔= 10 m s-2