Practice Questions

Q10.An ideal gas occupies a volume of 2 m3 at a pressure of 3 × 106 Pa. The energy of the gas is: (1) 108J (2) 9 × 106J (3) 3 × 102J (4) 6 × 104J

Q10.A heat source at T = 103 K is connected to another heat reservoir at T = 102 K by a copper slab which is 1 m thick. Given that the thermal conductivity of copper is 0 .1 W K−1 m−1 , the energy flux through it in the steady-state is: (1) 65 W m−2 (2) 120 W m−2 (3) 90 W m−2 (4) 200 W m−2

Q11.The given diagram shows four processes i.e., isochoric, isobaric, isothermal and adiabatic. The correct assignment of the processes, in the same order is given by: (1) a d b c (2) d a b c (3) a d c b (4) d a c b

Q11.For given gas at 1 atm pressure, rms speed of the molecules is 200 m/s at 127°C. At 2 atm pressure and at 227° C, the rms speed of the molecules will be: (1) 100 m/s (2) 80 m/s (3) 80√5 m/s (4) 100√5 m/s

Q11.A particle is executing simple harmonic motion (SHM) of amplitude A, along the x -axis, about x = 0. When its potential Energy (PE) equal kinetic energy (KE), the position of the particle will be: (1) A (2) A 2 (3) A (4) A 2√2 √2

Q11.The displacement of a damped harmonic oscillator is given by x(t) = e−0.1t cos(10πt + φ). Here t is in seconds. The time taken for its amplitude of vibration to drop to half of its initial value is close to: (1) 27 s (2) 4 s (3) 13 s (4) 7 s

Q12.A travelling harmonic wave is represented by the equation y(x, t) = 10−3 sin(50t + 2x), where x and y are in meter and t is in seconds. Which of the following is a correct statement about the wave? JEE Main 2019 (12 Jan Shift 1) JEE Main Previous Year Paper (1) The wave is propagating along the positive x - (2) The wave is propagating along the positive x - axis with speed 25 m s−1 axis with speed 100 m s−1 (3) The wave is propagating along the negative x - (4) The wave is propagating along the negative x - axis with speed 25 m s−1 axis with speed 100 m s−1

Q12.A gas can be taken from A to B via two different processes ACB and ADB. When path ACB is used 60 J of heat flows into the system and 30 J of work is done by the system. If the path ADB is used then work done by the system is 10 J, the heat flows into the system in the path ADB is: (1) 100 J (2) 20 J (3) 40 J (4) 80 𝐽

Q12.An HCl molecule has rotational, translational and vibrational motions. If the rms velocity of HCl molecules in − its gaseous phase is ν , m is its mass and kB is Boltzmann's constant, then its temperature will be: (1) m−ν 2 (2) m−ν 2 5kB 6kB (3) m−ν 2 (4) m−ν 2 3kB 7kB

Q13.A submarine experiences a pressure of 5.05 × 106 Pa at a depth of d1 in a sea. When it goes further to a depth of d2 , it experiences a pressure of 8.08 × 106 Pa . Then d2 - d1 is approximately (density of water = 103 kg / m3 and acceleration due to gravity = 10 ms-2 ): (1) 600 m (2) 500 m (3) 300 m (4) 400 m

Q13.A mixture of 2 moles of helium gas (atomic mass = 4u) , and 1 mole of argon gas (atomic mass = 40 u) is kept 𝑉𝑟𝑚𝑠ℎ𝑒𝑙𝑖𝑢𝑚 at 300 𝐾 in a container. The ratio of their rms speeds , is close to: 𝑉𝑟𝑚𝑠( 𝑎𝑟𝑔𝑜𝑛) (1) 0.45 (2) 2.24 (3) 0.32 (4) 3.16

Q14.A parallel plate capacitor with plates of area 1 m2 each, are at a separation of 0.1 m. If the electric field between the plates is 100 N/C, the magnitude of charge on each plate is: (Take ∈0= 8.85 × 10−12 N-m2C 2 ) (1) 8.85 x 10−10C (2) 6.85 x 10−10C (3) 9.85 x 10−10C (4) 7.85 x 10−10C

Q15.An electric field of 1000 V/m is applied to an electric dipole at angle of 45∘ . The value of electric dipole moment is 10−29C ⋅m. What is the potential energy of the electric dipole? (1) −20 × 10−18 J (2) −7 × 10−27 J (3) −10 × 10−29 J (4) −9 × 10−20 J

Q16.The charge on a capacitor plate in a circuit, as a function of time, is shown in the figure: What is the value of current at t = 4 s? (1) 1.5 μA (2) 2μA (3) Zero (4) 3μA

Q17.The correct figure that shows, schematically, the wave pattern produced by the superposition of two waves of frequencies 9 Hz and 11 Hz, is JEE Main 2019 (10 Apr Shift 2) JEE Main Previous Year Paper (1) (2) (3) (4)

Q17.A carbon resistance has a following colour code. What is the value of the resistance? (1) 6.4 MΩ ± 5% (2) 64 kΩ ± 10% (3) 530 kΩ ± 5% (4) 5.3 MΩ ± 5%

Q17.When the switch 𝑆, in the circuit shown, is closed, then the value of current 𝑖 will be: (1) 2 A (2) 5 A (3) 3 A (4) 4 A

Q17.To verify Ohm’s law, a student connects the voltmeter across the battery as shown in the figure. The measured voltage is plotted as a function of the current, and the following graph is obtained: If Vo is almost zero, identify the correct statement: (1) The emf of the battery is 1.5 V and its internal (2) The value of the resistance R is 1.5 Ω resistance is 1.5 Ω (3) The potential difference across the battery is (4) The emf of the battery is 1.5 V and the value of R 1.5 V when it sends a current of 1000 mA is 1.5 Ω

Q18.In the given circuit diagram, the currents, I1 = −0.3 A, I4 = 0.8 A and I5 = 0.4 A, are flowing as shown. The currents I2, I3 and I6, respectively, are: (1) 0.4A, 1.1A, 0.4A (2) 1.1A, −0.4A, 0.4A (3) 1.1A, 0.4A, 0.4A (4) −0. 4A, 0. 4A, 1. 1A

Q18.A uniform metallic wire has a resistance of 18 Ω and is bent into an equilateral triangle. Then, the resistance between any two vertices of the triangle is: (1) 2 Ω (2) 12 Ω (3) 8 Ω (4) 4 Ω

Q18.A 200 Ω resistor has certain colour code. If one replaced the red colour by green in the code, the new resistance will be: (1) 300 Ω (2) 100 Ω (3) 400 Ω (4) 500 Ω

Q18.The resistance of a galvanometer is 50 ohm and the maximum current which can be passed through it is 0.002 A. What resistance must be connected to it in order to convert it into an ammeter of range 0 −0.5 A? (1) 0.2 ohm (2) 0.5 ohm (3) 0.002 ohm (4) 0.02 ohm

Q19.A cell of internal resistance r drives current through an external resistance R . The power delivered by the cell to the external resistance will be maximum when: (1) R = 2r (2) R = r (3) R = 1000 r (4) R = 0.001 r

Q20.The Wheatstone bridge shown in the figure below, gets balanced when the carbon resistor used as R1 has the colour code (orange, red, brown). The resistors R2 and R4 are 80 Ω and 40 Ω , respectively. Assuming that the colour code for the carbon resistors gives their accurate values, the colour code for the carbon resistor, used as R3 , would be JEE Main 2019 (10 Jan Shift 2) JEE Main Previous Year Paper (1) brown, blue, black. (2) brown, blue, brown. (3) grey, black, brown. (4) red, green, brown.

Q20.A moving coil galvanometer has resistance 50 Ω and it indicates full deflection at 4 mA current. A voltmeter is made using this galvanometer and a 5 kΩ resistance. The maximum voltage, that can be measured using this voltmeter, will be close to: (1) 40 V (2) 15 V (3) 20 V (4) 10 V