Practice Questions

Q11. Given below are two statements. One is labelled as Assertion A and the other is labelled as Reason R. Assertion A : If dQ and dW represent the heat supplied to the system and the work done on the system respectively. Then according to the first law of thermodynamics dQ = dU −dW . Reason R : First law of thermodynamics is based on law of conservation of energy. In the light of the above statements, choose the correct answer from the option given below : (1) A is correct but R is not correct (2) A is not correct but R is correct (3) Both A and R are correct and R is the correct (4) Both A and R are correct but R is not the correct explanation of A explanation of A

Q11.For a uniformly charged thin spherical shell, the electric potential 𝑉 radially away from the centre 𝑂 of shell can be graphically represented as (1) (2) (3) (4) JEE Main 2023 (06 Apr Shift 1) JEE Main Previous Year Paper

Q12.A flask contains hydrogen and oxygen in the ratio of 2 : 1 by mass at temperature 27 °C. The ratio of average kinetic energy per molecule of hydrogen and oxygen respectively is : (1) 2 : 1 (2) 1 : 1 (3) 1 : 4 (4) 4 : 1

Q12.The temperature of an ideal gas is increased from 200 K to 800 K . If r.m.s. speed of gas at 200 K is v0 . Then, r.m.s. speed of the gas at 800 K will be: (1) v0 (2) v0 4 (3) 4v0 (4) 2v0

Q12.The drift velocity of electrons for a conductor connected in an electrical circuit is 𝑉𝑑. The conductor is now replaced by another conductor with same material and same length but double the area of cross-section. The applied voltage remains same. The new drift velocity of electrons will be JEE Main 2023 (31 Jan Shift 1) JEE Main Previous Year Paper 𝑉𝑑 (1) 𝑉𝑑 (2) 2 (3) 𝑉𝑑 (4) 2𝑉𝑑 4

Q12.For three low density gases A, B, C pressure versus temperature graphs are plotted while keeping them at constant volume, as shown in the figure The temperature corresponding to the point ′K′ is: (1) −273°C (2) −100°C (3) –373°C (4) −40°C

Q12.The temperature at which the kinetic energy of oxygen molecules becomes double than its value at 27°C is (1) 927°C (2) 327°C (3) 1227°C (4) 627°C

Q12.A bicycle tyre is filled with air having pressure of 270 kPa at 27°C. The approximate pressure of the air in the tyre when the temperature increases to 36°C is (1) 270 kPa (2) 262 kPa (3) 278 kPa (4) 360 kPa

Q13.For a simple harmonic motion in a mass spring system shown, the surface is frictionless. When the mass of the block is 1 kg, the angular frequency is ω1 . When the mass block is 2 kg the angular frequency is ω2 . The ratio JEE Main 2023 (30 Jan Shift 2) JEE Main Previous Year Paper ω2 is : ω1 (1) √2 (2) 1 √2 (3) 2 (4) 12

Q13.For a solid rod, the Young's modulus of elasticity is 3. 2 × 1011 N m−2 and density is 8 × 103 kg m−3 . The velocity of longitudinal wave in the rod will be (1) 145. 75 × 103 m s−1 (2) 3. 65 × 103 m s−1 (3) 18. 96 × 103 m s−1 (4) 6. 32 × 103 m s−1

Q13.Match List I with List II : List I List II AIsothermal I Work done by the gas decreases internal energy Process B Adiabatic Process II No change in internal energy The heat absorbed goes partly to increase internal energy and partly to do C Isochoric Process III work DIsobaric Process IVNo work is done on or by the gas Choose the correct answer from the options given below : (1) A-II, B-I, C-III, D-IV (2) A-II, B-I, C-IV, D-III (3) A-I, B-II, C-IV, D-III (4) A-I, B-II, C-III, D-IV

Q13.The root mean square velocity of molecules of gas is (1) Proportional to square of temperature ( T 2 ). (2) Inversely proportional to square root of temperature ( ). √1T (3) Proportional to square root of temperature √T . (4) Proportional to temperature (T).

Q14.The amplitude of magnetic field in an electromagnetic wave propagating along 𝑦-axis is 6 . 0 × 10 – 7 T. The maximum value of electric field in the electromagnetic wave is (1) 2 × 1015 V m – 1 (2) 180 V m – 1 (3) 6 . 0 × 10 – 7 V m – 1 (4) 5 × 1014 V m – 1

Q14.For the plane electromagnetic wave given by 𝐸= 𝐸0sin ( 𝜔𝑡– 𝑘𝑥) and 𝐵= 𝐵0sin ( 𝜔𝑡- 𝑘𝑥) , the ratio of average electric energy density to average magnetic energy density is 1 (1) (2) 2 2 (3) 4 (4) 1

Q14.A mass m attached to free end of a spring executes SHM with a period of 1 s. If the mass is increased by 3 kg the period of oscillation increases by one second, the value of mass m is ________ kg.

Q14.Choose the correct length (L) versus square of time period (T2) ) graph for a simple pendulum executing simple harmonic motion. JEE Main 2023 (01 Feb Shift 2) JEE Main Previous Year Paper (1) (2) (3) (4)

Q14.A rod with circular cross-section area 2 cm2 and length 40 cm is wound uniformly with 400 turns of an insulated wire. If a current of 0 . 4 A flows in the wire windings, the total magnetic flux produced inside windings is 4π × 10-6 Wb. The relative permeability of the rod is (Given : Permeability of vacuum μ0 = 4π × 10-7 N A-2) 32 (1) 12 . 5 (2) 5 (3) 125 (4) 5 16

Q14.The magnetic moments associated with two closely wound circular coils 𝐴 and 𝐵 of radius 𝑟𝐴= 10 cm and 𝑟𝐵= 20 cm respectively are equal if: (Where 𝑁𝐴, 𝐼𝐴 and 𝑁𝐵, 𝐼𝐵 are number of turn and current of 𝐴 and 𝐵 respectively) (1) 2𝑁𝐴𝐼𝐴= 𝑁𝐵𝐼𝐵 (2) 𝑁𝐴= 2𝑁𝐵 (3) 𝑁𝐴𝐼𝐴= 4𝑁𝐵𝐼𝐵 (4) 4𝑁𝐴𝐼𝐴= 𝑁𝐵𝐼𝐵

Q14.The ratio of speed of sound in hydrogen gas to the speed of sound in oxygen gas at the same temperature is: (1) 1 : 2 (2) 4 : 1 (3) 1 : 4 (4) 1 : 1

Q15.Match List I with List II List I List II A Troposphere I Approximate 65 −75 km over Earth’s surface B E-Part of Stratosphere II Approximate 300 km over Earth’s surface C F2 -Part of Thermosphere III Approximate 10 km over Earth’s surface D D-Part of Stratosphere IV Approximate 100 km over Earth’s surface Choose the correct answer from the options given below : (1) A-III, B-IV, C-II, D-I (2) A-I, B-II, C-IV, D-III (3) A-I, B-IV, C-III, D-II (4) A-III, B-II, C-I, D-IV

Q15.A point charge 2 × 10–2 C is moved from P to S in a uniform electric field of 30 N C–1 directed along positive x-axis. If coordinates of P and S are (1, 2, 0) m and (0, 0, 0) m respectively, the work done by electric field will be (1) 1200 mJ (2) 600 mJ (3) −600 mJ (4) −1200 mJ

Q15.Electric potential at a point P due to a point charge of 5 × 10−9 C is 50 V . The distance of P from the point charge is: (Assume, 1 = 9 × 109 N m2 C−2 ) 4πε0 (1) 9 cm (2) 3 cm (3) 0. 9 cm (4) 90 cm

Q15.An organ pipe 40 cm long is open at both ends. The speed of sound in air is 360 m s−1 . The frequency of the second harmonic is _ ________ Hz.

Q15.Considering a group of positive charges, which of the following statements is correct? (1) Net potential of the system cannot be zero at a (2) Net potential of the system at a point can be zero point but net electric field can be zero at that but net electric field can't be zero at that point point (3) Both the net potential and the net field can be (4) Both the net potential and the net electric field zero at a point cannot be zero at a point

Q15.Match the List-I with List-II: List I List II A Microwaves I Radioactive decay of the nucleus B Gamma rays II Rapid acceleration and deceleration of electron in aerials C Radio waves III Inner shell electrons D X-rays IV Klystron valve Choose the correct answer from the options given below: (1) A-I, B-II, C-III, D-IV (2) A-IV, B-I, C-II, D-III (3) A-I, B-III, C-IV, D-II (4) A-IV, B-III, C-II, D-I Q16.‘𝑛’ polarizing sheets are arranged such that each makes an angle 45° with the proceeding sheet. An 𝐼 unpolarized light of intensity 𝐼 is incident into this arrangement. The output intensity is found to be . The 64 value of 𝑛 will be: (1) 3 (2) 6 (3) 5 (4) 4