Practice Questions

Q9. Consider a mixture of gas molecule of types A, B and C having masses mA < mB < mC. The ratio of their root mean square speeds at normal temperature and pressure is: (1) vA = vB = vC = 0 (2) 1 > 1 > 1 vA vB vC (3) vA = vB ≠vC (4) 1 < 1 < 1 vA vB vC

Q9. Which of the following equations represents a travelling wave? (1) y = A sin(15x −2t) (2) y =Aex cos(ωt −θ) (3) y = Ae−x2(vt + θ) (4) y = A sin x cos ωt

Q9. If the R.M.S. speed of oxygen molecules at 0°C is 160 m s−1 . Find the R.M.S. speed of hydrogen molecules at 0°C . (1) 40 m s−1 (2) 80 m s−1 (3) 640 m s−1 (4) 332 m s−1

Q9. If the time period of a two meter long simple pendulum is 2 s, the acceleration due to gravity at the place where pendulum is executing S.H.M. is: (1) 2π2 m s−2 (2) 16 m s−2 (3) π2 m s−2 (4) 9. 8 m s−2

Q10.A resistor develops 500 J of thermal energy in 20 s when a current of 1. 5 A is passed through it. If the current is increased from 1. 5 A to 3 A , what will be the energy developed in 20 s. (1) 1500 J (2) 1000 J (3) 500 J (4) 2000 J → → →

Q10.A particle starts executing simple harmonic motion (SHM) of amplitude a and total energy E. At any instant, its kinetic energy is 3E , then its displacement y is given by: 4 (1) y = a (2) y = a √2 (3) y = a√32 (4) y = a2

Q10.Consider a sample of oxygen behaving like an ideal gas. At 300 K, the ratio of root-mean-square (RMS) velocity to the average velocity of the gas molecule would be : (Molecular weight of oxygen is 32 g mol−1; R = 8. 3 J K−1 mol−1 ) (1) √33 (2) √83 (3) √3π8 (4) √8π3

Q10.Two particles A and B of equal masses are suspended from two massless springs of spring constants K1 and K2 respectively.If the maximum velocities during oscillations are equal, the ratio of the amplitude of A and B is (1) K2 (2) K1 K1 K2 (3) √K1K2 (4) √K2K1

Q10.A 25 m long antenna is mounted on an antenna tower. The height of the antenna tower is 75 m . The wavelength (in meter) of the signal transmitted by this antenna would be : (1) 300 (2) 400 (3) 200 (4) 100

Q10.The temperature θ at the junction of two insulating sheets, having thermal resistances R1 and R2 as well as top and bottom temperatures θ1 and θ2 (as shown in figure) is given by : (1) θ1R2−θ2R1 (2) θ2R2−θ1R1 R2−R1 R2−R1 (3) θ1R2+θ2R1 (4) θ1R1+θ2R2 R1+R2 R1+R2

Q10.A cylindrical container of volume 4. 0 × 10−3 m3 contains one mole of hydrogen and two moles of carbon dioxide. Assume the temperature of the mixture is 400 K. The pressure of the mixture of gases is : [Take gas constant as 8. 3 J mol−1 K−1] (1) 24. 9 × 103 Pa (2) 249 × 101 Pa (3) 24. 9 × 105 Pa (4) 24. 9 Pa

Q10.In a ferromagnetic material, below the curie temperature, a domain is defined as: (1) a macroscopic region with saturation magnetization. (2) a macroscopic region with consecutive magnetic dipoles oriented in opposite direction. (3) a macroscopic region with zero magnetization. (4) a macroscopic region with randomly oriented magnetic dipoles. JEE Main 2021 (25 Feb Shift 2) JEE Main Previous Year Paper

Q11.A charge Q is moving dl distance in the magnetic field B. Find the value of work done by B. (1) 1 (2) Infinite (3) Zero (4) −1 → x . A square loop of side d is placed with its edges along

Q11.A particle executes S.H.M., the graph of velocity as a function of displacement is : (1) a circle (2) a helix (3) a parabola (4) an ellipse

Q11.For what value of displacement the kinetic energy and potential energy of a simple harmonic oscillation become equal? JEE Main 2021 (17 Mar Shift 1) JEE Main Previous Year Paper (1) x = 0 (2) x = ±A (3) x = ± A (4) x = A2 √2

Q11. A soft ferromagnetic material is placed in an external magnetic field. The magnetic domains: (1) have no relation with external magnetic field. (2) decrease in size and changes orientation. (3) increase in size but no change in orientation. (4) may increase or decrease in size and change its orientation.

Q11.Two ideal electric dipoles A and B, having their dipole moment p1 and p2 respectively are placed on a plane with their centres at O as shown in the figure. At point C on the axis of dipole A, the resultant electric field is making an angle of 37° with the axis. The ratio of the dipole moment of A and B, p1 is : ( take sin 37°= 53 ) p2 (1) 3 (2) 3 8 2 (3) 2 (4) 4 3 3

Q12.The relative permittivity of distilled water is 81. The velocity of light in it will be: (Given μr = 1) (1) 4. 33 × 107 m s−1 (2) 2. 33 × 107 m s−1 (3) 3. 33 × 107 m s−1 (4) 5. 33 × 107 m s−1

Q12.Match List I with List II. List I List II (a) Rectifier (i) Used either for stepping up or stepping down the A.C. voltage (b)Stabilizer (ii) Used to convert A.C. voltage into D.C. voltage (c) Transformer(iii)Used to remove any ripple in the rectified output voltage Used for constant output voltage even when the input voltage (d)Filter (iv) or load current change Choose the correct answer from the options given below: (1) (a) −(ii), (b) −(iv), (c) −(i), (d) −(iii) (2) (a) −(ii), (b) −(i), (c) −(iv), (d) −(iii) (3) (a) −(ii), (b) −(i), (c) −(iii), (d) −(iv) (4) (a) −(iii), (b) −(iv), (c) −(i), (d) −(ii)

Q12.For full scale deflection of total 50 divisions, 50 mV voltage is required in galvanometer. The resistance of galvanometer if its current sensitivity is 2 div / mA will be: (1) 1 Ω (2) 2 Ω (3) 5 Ω (4) 4 Ω

Q12.The correct relation between the degrees of freedom f and the ratio of specific heat γ is: (1) f = γ−12 (2) f = γ+12 (3) f = γ+12 (4) f = γ+11

Q13.A plane electromagnetic wave of frequency 100 MHz is traveling in a vacuum along the x−direction. At a → → particular point in space and time, B = 2. 0 × 10−8 ˆkT⋅ (where, ˆk is unit vector along z−direction) What is E at this point? (1) 0. 6ˆj V m−1 (2) 6. 0ˆk V m−1 (3) 6. 0ˆj V m−1 (4) 0. 6ˆk V m−1

Q13.For the given circuit, comment on the type of transformer used : (1) Auxilliary transformer (2) Auto transformer (3) Step-up transformer (4) Step down transformer

Q13.In a circuit consisting of a capacitance and a generator with alternating emf, Eg = Egosinωt, VC and IC are the voltage and current. Correct phasor diagram for such circuit is JEE Main 2021 (22 Jul Shift 1) JEE Main Previous Year Paper (1) (2) (3) (4)

Q13.The colour coding on a carbon resistor is shown in the given figure. The resistance value of the given resistor is: (1) (7500 ± 375)Ω (2) (5700 ± 285)Ω (3) (7500 ± 755)Ω (4) (5700 ± 375)Ω