Practice Questions

Q15.A coil is placed in a magnetic field →𝐵 as shown below : → A current is induced in the coil because 𝐵 is : (1) parallel to the plane of coil and increasing with (2) outward and increasing with time time (3) outward and decreasing with time (4) parallel to the plane of coil and decreasing with time + ^j cos𝑘𝑧- 𝜔𝑡 where ^i, ^j

Q15.The electric field in a plane electromagnetic wave is given by, E = 50 sin(500x −10 × 1010t) V m−1 . The velocity of an electromagnetic wave in this medium is: (Given c = the speed of light in vacuum). (1) 23 c (2) c (3) 2c (4) 23 c

Q15.Match List-I with List-II List-i List-II π 2 ; current Phase difference between current and voltage in a purely a i leads resistive AC circuit voltage bPhase difference between current and ii zero voltage in a pure inductive AC circuit Phase difference between current and π 2 ; current lags c iii voltage in a pure capacitive AC circuit voltage dPhase difference between current and iv tan−1( XC−XLR ) voltage in an LCR series circuit Choose the most appropriate answer from the options given below : (1) (a) −(i), (b) −(iii), (c) −(iv), (d) −(ii) (2) (a) −(ii), (b) −(iv), (c) −(iii), (d) −(i) (3) (a) −(ii), (b) −(iii), (c) −(iv), (d) −(i) (4) (a )-( ii ) , (b) −(iii), (c) −(i), (d) −(iv)

Q16.What happens to the inductive reactance and the current in a purely inductive circuit if the frequency is halved ? (1) Both, inductive reactance and current will (2) Inductive reactance will be halved and be halved. current will be doubled.. (3) Inductive reactance will be doubled and (4) Both, inducting reactance and current will be current will be halved. doubled JEE Main 2021 (17 Mar Shift 2) JEE Main Previous Year Paper

Q16.The magnetic susceptibility of a material of a rod is 499. Permeability in vacuum is 4π × 10−7 Hm−1. Absolute permeability of the material of the rod is (1) 4π × 10−4 Hm−1 (2) 2π × 10−4 Hm−1 (3) 3π × 10−4 Hm−1 (4) π × 10−4 Hm−1 JEE Main 2021 (20 Jul Shift 2) JEE Main Previous Year Paper

Q16.A 100Ω resistance, a 0. 1μF capacitor and an inductor are connected in series across a 250 V supply at variable frequency. Calculate the value of inductance of inductor at which resonance will occur. Given that the resonant frequency is 60 Hz. (1) 0. 70H (2) 70. 3 mH (3) 7. 03 × 10−5H (4) 70. 3 H

Q17.The wavelength of the photon emitted by a hydrogen atom when an electron makes a transition from n = 2 to n = 1 state is: (1) 121. 8 nm (2) 194. 8 nm (3) 490. 7 nm (4) 913. 3 nm JEE Main 2021 (25 Feb Shift 2) JEE Main Previous Year Paper

Q17.If an electron is moving in the nth orbit of the hydrogen atom, then its velocity (vn) for the nth orbit is given as: (1) vn ∝n (2) vn ∝1n (3) vn ∝n2 (4) vn ∝ n21

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

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.In a Young's double slit experiment, the width of the one of the slit is three times the other slit. The amplitude of the light coming from a slit is proportional to the slit-width. Find the ratio of the maximum to the minimum intensity in the interference pattern. JEE Main 2021 (24 Feb Shift 1) JEE Main Previous Year Paper (1) 1: 4 (2) 2: 1 (3) 3: 1 (4) 4: 1

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 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)

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

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

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.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

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 → → → → → →

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.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.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.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 → +