Practice Questions

Q20.To radiate EM signal of wavelength 𝜆 with high efficiency, the antennas should have a minimum size equal to: (1) 2𝜆 (2) 𝜆 2 (3) 𝜆 (4) 𝜆 4

Q20.A solenoid of 1200 turns is wound uniformly in a single layer on a glass tube 2 m long and 0. 2 m in diameter. The magnetic intensity at the center of the solenoid when a current of 2 A flows through it is: (1) 2. 4 × 103 A m−1 (2) 1. 2 × 103 A m−1 (3) 1 A m−1 (4) 2. 4 × 10−3 A m−1

Q20.A single turn current loop in the shape of a right angle triangle with sides 5 cm, 12 cm, 13 cm is carrying a current of 2 A . The loop is in a uniform magnetic field of magnitude 0. 75 T whose direction is parallel to the current in the 13 cm side of the loop. The magnitude of the magnetic force on the 5 cm side will be 130x N . The value of x is _______.

Q20.A carrier wave of amplitude 15 V is modulated by a sinusoidal base band signal of amplitude 3 V. The ratio of maximum amplitude to minimum amplitude in an amplitude modulated wave is 3 (1) 2 (2) 2 (3) 1 (4) 5

Q20.A current carrying rectangular loop PQRS is made of uniform wire. The length PR = QS = 5 cm and PQ = RS = 100 cm. If ammeter current reading changes from I to 2I , the ratio of : f PQ)2I is: magnetic forces per unit length on the wire PQ due to wire RS in the two cases respectively (f PQI JEE Main 2023 (30 Jan Shift 2) JEE Main Previous Year Paper (1) 1 : 2 (2) 1 : 4 (3) 1 : 5 (4) 1 : 3

Q21.An alternating voltage source V = 260 sin(628t) is connected across a pure inductor of 5 mH . Inductive reactance in the circuit is: (1) 3. 14Ω (2) 6. 28Ω (3) 0. 5Ω (4) 0. 318Ω

Q21.A small particle moves to position 5 ^𝑖- 2 ^𝑗+ ^𝑘 from its initial position 2 ^𝑖+ 3 ^𝑗- 4 ^𝑘 under the action of force 5 ^𝑖+ 2 ^𝑗+ 7 ^𝑘 N. The value of work done will be ______ J.

Q21.An emf of 0. 08 V is induced in a metal rod of length 10 cm held normal to a uniform magnetic field of 0. 4 T, when move with a velocity of: (1) 0. 5 m s−1 (2) 20 m s−1 (3) 3. 2 m s−1 (4) 2 m s−1

Q21.In an LC oscillator, if values of inductance and capacitance become twice and eight times, respectively, then the resonant frequency of oscillator becomes x times its initial resonant frequency ω0 . The value of x is: (1) 1/4 (2) 16 (3) 1/16 (4) 4

Q21.An electron is allowed to move with constant velocity along the axis of current carrying straight solenoid. (A) The electron will experience magnetic force along the axis of the solenoid. (B) The electron will not experience magnetic force. (C) The electron will continue to move along the axis of the solenoid. (D) The electron will be accelerated along the axis of the solenoid. (E) The electron will follow parabolic path-inside the solenoid. Choose the correct answer from the option given below: (1) B, C and D only (2) A and D only (3) B and C only (4) B and E only

Q21.A charge particle moving in magnetic field B, has the components of velocity along B as well as perpendicular to B. The path of the charge particle will be (1) helical path with the axis perpendicular to the (2) helical path with the axis along magnetic field B direction of magnetic field B (3) circular path (4) straight along the direction of magnetic field B

Q22.Which of the following are true? A. Speed of light in vacuum is dependent on the direction of propagation. B. Speed of light in a medium is independent of the wavelength of light. C. The speed of light is independent of the motion of the source. D. The speed of light in a medium is independent of intensity. Choose the correct answer from the question given below : (1) A and C only (2) B and D only (3) B and C only (4) C and D only

Q22.In the given circuit, rms value of current (Irms) through the resistor R is : (1) 2 A (2) 21 A (3) 20 A (4) 2√2 A

Q23.Match List I and List II List I List II A Microwaves I Physiotherapy B UV rays II Treatment of cancer JEE Main 2023 (31 Jan Shift 2) JEE Main Previous Year Paper C Infra-red rays III Lasik eye surgery D X-rays IV Aircraft navigation Choose the correct answer from the option given below: (1) A-II, B-IV, C-III, D-I (2) A-IV, B-I, C-II, D-III (3) A-IV, B-III, C-I, D-II (4) A-III, B-II, C-I, D-IV

Q23.A vessel of depth d is half filled with oil of refractive index n1 and the other half is filled with water of refractive index n2. The apparent depth of this vessel when viewed from above will be- (1) 2d(n1+n2) (2) d(n1+n2) n1+n2 2n1n2 (3) dn1n2 (4) dn1n2 2(n1+n2) (n1+n2)

Q23.A wire of length 1 m moving with velocity 8 m s−1 at right angles to a magnetic field of 2 T. The magnitude of induced emf, between the ends of wire will be ___________. (1) 20 V (2) 8 V (3) 12 V (4) 16 V

Q23.All electromagnetic wave is transporting energy in the negative z direction. At a certain point and certain time the direction of electric field of the wave is along positive y direction. What will be the direction of the magnetic field of the wave at that point and instant? JEE Main 2023 (25 Jan Shift 1) JEE Main Previous Year Paper (1) Positive direction of x (2) Positive direction of z (3) Negative direction of x (4) Negative direction of y

Q23.The electric field and magnetic field components of an electromagnetic wave going through vacuum is described by Ex = E0 sin(kz −ωt) By = B0 sin(kz −ωt) Then the correct relation between E0 and B0 is given by (1) E0B0 = ωk (2) E0 = kB0 (3) kE0 = ωB0 (4) ωE0 = kB0

Q23.The ratio of average electric energy density and total average energy density of electromagnetic wave is: (1) 2 (2) 1 (3) 3 (4) 21

Q23.A capacitor of capacitance 150. 0 μF is connected to an alternating source of emf given by E = 36 sin(120πt) V. The maximum value of current in the circuit is approximately equal to: (1) 2 A (2) √2 A (3) 2√2 A (4) 1 A √2 → →

Q24.In a reflecting telescope, a secondary mirror is used to: (1) reduce the problem of mechanical support (2) make chromatic aberration zero (3) move the eyepiece outside the telescopic tube (4) remove spherical aberration

Q25.The difference between threshold wavelengths for two metal surfaces A and B having work function ϕA = 9 eV and ϕB = 4. 5 eV in nm is: {Given, hc = 1242 eV nm } (1) 540 (2) 276 (3) 264 (4) 138

Q25.The threshold wavelength for photoelectric emission from a material is 5500 A . Photoelectrons will be emitted, when this material is illuminated with monochromatic radiation from a A. 75 W infra-red lamp B. 10 W infra-red lamp C. 75 W ultra-violet lamp D. 10 W ultra-violet lamp Choose the correct answer from the options given below : (1) B and C only (2) A and D only (3) C only (4) C and D only

Q25.Match List I and List II → → A Gauss’s Law in Electrostatics I ∮ E ⋅ dl = −dϕBdt → → B Faraday's Law II ∮ B ⋅d A = 0 → → C Gauss’s Law in Magnetism III ∮ B ⋅d l = μ0ic + μ0 ∈0 dϕEdt q D Ampere-Maxwell Law IV ∮→E ⋅d→s= ∈0 Choose the correct answer from the options given below : (1) A-IV, B-I, C-II, D-III (2) A-I, B-II, C-III, D-IV (3) A-III, B-IV, C-I, D-II (4) A-II, B-III, C-IV, D-I JEE Main 2023 (25 Jan Shift 2) JEE Main Previous Year Paper

Q25.When one light ray is reflected from a plane mirror with 30° angle of reflection, the angle of deviation of the ray after reflection is: JEE Main 2023 (11 Apr Shift 2) JEE Main Previous Year Paper (1) 120° (2) 110° (3) 140° (4) 130°