Practice Questions

Q24.The diameter of an air bubble which was initially 2 mm, rises steadily through a solution of density $1750 \mathrm{~kg} / \mathrm{m}^3$ at the rate of $0.35 \mathrm{~cm} / \mathrm{s}$. Coefficient of viscosity of the solution is ______ (Assume mass of the bubble to be negligible) (Answer in Poise to the nearest integer)

Q24.One mole of a monoatomic gas is mixed with three moles of a diatomic gas. The molecular specific heat of mixture at constant volume is α2 R J mol K−1 ; then the value of α will be _____ . (Assume that the given 4 diatomic gas has no vibrational mode.)

Q24.A unit scale is to be prepared whose length does not change with temperature and remains 20 cm, using a bimetallic strip made of brass and iron each of different length. The length of both components would change in such a way that difference between their lengths remains constant. If length of brass is 40 cm and length of iron will be _____ cm. 𝛼iron = 1 . 2 × 10-5 K-1 and 𝛼brass = 1 . 8 × 10-5 K-1.

Q24.A capacitor of capacitance 50 pF is charged by 100 V source. It is then connected to another uncharged identical capacitor. Electrostatic energy loss in the process is____ nJ .

Q24.Two waves executing simple harmonic motion travelling in the same direction with same amplitude and frequency are superimposed. The resultant amplitude is equal to the √3 times of amplitude of individual motions. The phase difference between the two motions is _____ (degree)

Q24.Moment of Inertia (M.I.) of four bodies having same mass 𝑀 and radius 2𝑅 are as follows 𝐼1 = M.I. of solid sphere about its diameter 𝐼2 = M.I. of solid cylinder about its axis 𝐼3 = M.I. of solid circular disc about its diameter 𝐼4 = M.I. of thin circular ring about its diameter If 2𝐼2 + 𝐼3 + 𝐼4 = 𝑥𝐼1 then the value of 𝑥 will be _____ .

Q24.As per given figures, two springs of spring constants 𝐾 and 2 K are connected to mass m. If the period of oscillation in figure (a) is 3 s, then the period of oscillation in figure (b) will be √𝑥 s. The value of 𝑥 is _____ .

Q24.Two coils require 20 minutes and 60 minutes respectively to produce same amount of heat energy when connected separately to the same source. If they are connected in parallel arrangement to the same source; the time required to produce same amount of heat by the combination of coils, will be _____ min.

Q24.The displacement current of 4. 425 μA is developed in the space between the plates of parallel plate capacitor when voltage is changing at a rate of 106 V s−1 . The area of each plate of the capacitor is 40 cm2 . The distance between each plate of the capacitor is x × 10−3 m . The value of x is , (Permittivity of free space, ε0 = 8. 85 × 10−12 C2 N−1 m−2 ) _______

Q24.A mass 0. 9 kg, attached to a horizontal spring, executes SHM with an amplitude A1 . When this mass passes through its mean position, then a smaller mass of 124 g is placed over it and both masses move together with amplitude A2 . If the ratio A2A1 is α−1α , then the value of α will be _____ .

Q25.The variation of applied potential and current flowing through a given wire is shown in figure. The length of wire is 31. 4 cm. The diameter of wire is measured as 2. 4 cm. The resistivity of the given wire is measured as x × 10−3 Ω cm. The value of x is _____ . [Take π = 3. 14 ]

Q25.A capacitor C1 of capacitance 5 μF is charged to a potential of 30 V using a battery. The battery is then removed and the charged capacitor is connected to an uncharged capacitor C2 of capacitance 10 μF as shown in figure. When the switch is closed charge flows between the capacitors. At equilibrium, the charge on the capacitor C2 is _____ μC.

Q25.The metallic bob of simple pendulum has the relative density 5. The time period of this pendulum is 10 s. If the metallic bob is immersed in water, then the new time period becomes 5√𝑥 s. The value of 𝑥 will be _____ .

Q25.A potentiometer wire of length 10 m and resistance 20 Ω is connected in series with a 25 V battery and an external resistance 30 Ω. A cell of emf E in secondary circuit is balanced by 250 cm long potentiometer wire. The value of E (in volt) is x . The value of x is _____ . 10 JEE Main 2022 (24 Jun Shift 2) JEE Main Previous Year Paper

Q25.A 1 m long copper wire carries a current of 1 A . If the cross section of the wire is 2. 0 mm2 and the resistivity of copper is 1. 7 × 10−8 Ω m. The force experienced by moving electron in the wire is _____ ×10−23 N (Charge of electron = 1. 6 × 10−19C )

Q25.A parallel plate capacitor is made up of stair like structure with a plate area A of each stair and that is x ε0 A , The connected with a wire of length b, as shown in the figure. The capacitance of the arrangement is b 15 value of x is _____ .

Q25.A wire of length 30 cm, stretched between rigid supports, has it's nth and (n + 1)th harmonics at 400 Hz and 450 Hz, respectively. If tension in the string is 2700 N , it's linear mass density is _____ kg m−1 .

Q25.Two light beams of intensities 4I and 9I interfere on a screen. The phase difference between these beams on the screen at point A is zero and at point B is π. The difference of resultant intensities, at the point A and B, will be _____ I .

Q25.A heat engine operates with the cold reservoir at temperature 324 K. The minimum temperature of the hot reservoir, if the heat engine takes 300 J heat from the hot reservoir and delivers 180 J heat to the cold reservoir per cycle, is _____ K .

Q25.A steam engine intakes 50 g of steam at 100°C per minute and cools it down to 20°C. If latent heat of vaporization of steam is 540 cal g-1, then the heat rejected by the steam engine per minute is _____ × 103 cal (Given : specific heat capacity of water : 1 cal g-1∘C-1)

Q25.An ideal fluid of density 800 kg m−3 , flows smoothly through a bent pipe (as shown in figure) that tapers in cross-sectional area from a to a . The pressure difference between the wide and narrow sections of pipe is 2 4100 Pa . At wider section, the velocity of fluid is √x6 m s−1 for x = _____ . (Given g = 10 m s−2 )

Q25.The frequency of echo will be _____ Hz if the train blowing a whistle of frequency 320 Hz is moving with a velocity of 36 km h-1 towards a hill from which an echo is heard by the train driver. Velocity of sound in air JEE Main 2022 (28 Jul Shift 1) JEE Main Previous Year Paper is 330 m s-1.

Q25.In a potentiometer arrangement, a cell gives a balancing point at 75 cm length of wire. This cell is now replaced by another cell of unknown emf. If the ratio of the emf's of two cells respectively is 3 : 2 , the difference in the balancing length of the potentiometer wire in above two cases will be _____ cm.

Q25.Two parallel plate capacitors of capacity C and 3C are connected in parallel combination and charged to a potential difference 18 V . The battery is then disconnected and the space between the plates of the capacitor of capacity C is completely filled with a material of dielectric constant 9 . The final potential difference across the combination of capacitors will be _____ V .

Q25.Three point charges of magnitude 5 𝜇C, 0 . 16 𝜇C and 0 . 3 𝜇C are located at the vertices 𝐴, 𝐵, 𝐶 of a right angled triangle whose sides are 𝐴𝐵= 3 cm, 𝐵𝐶= 3√2 cm and 𝐶𝐴= 3 cm and point 𝐴 is the right angle corner. Charge at point 𝐴 experiences _____ N of electrostatic force due to the other two charges.