Practice Questions

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.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.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 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 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.A 220 V, 50 Hz AC source is connected to a 25 V, 5 W lamp and an additional resistance R in series (as shown in figure) to run the lamp at its peak brightness, then the value of R (in ohm) will be

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.An observer is riding on a bicycle and moving towards a hill at 18 km h-1. He hears a sound from a source at some distance behind him directly as well as after its reflection from the hill. If the original frequency of the sound as emitted by source is 640 Hz and velocity of the sound in air is 320 m s-1, the beat frequency between the two sounds heard by observer will be _____ Hz.

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.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.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.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.

Q25.Two satellites 𝑆1 and 𝑆2 are revolving in circular orbits around a planet with radius 𝑅𝐼= 3200 km and 𝑅2 = 800 km respectively. The ratio of speed of satellite 𝑆1 to the speed of satellite 𝑆2 in their respective 1 orbits would be where 𝑥= 𝑥

Q25.The total internal energy of two mole monoatomic ideal gas at temperature T = 300 K will be _____ J. (Given R = 8. 31 J mol−1 ⋅K)

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 .

Q26.As shown in the figure an inductor of inductance 200 mH is connected to an AC source of emf 220 V and frequency 50 Hz. The instantaneous voltage of the source is 0 V when the peak value of current is √aπ A . The value of a is _____ .

Q26.An inductor of 0. 5 mH , a capacitor of 200 μF and a resistor of 2 Ω are connected in series with a 220 V ac source. If the current is in phase with the emf, the frequency of ac source will be ______ ×102 Hz .

Q26.Resistance are connected in a meter bridge circuit as shown in the figure. The balancing length l1 is 40 cm. Now an unknown resistance x is connected in series with P and new balancing length is found to be 80 cm measured from the same end. Then the value of x will be _____ Ω.

Q26.Two electric dipoles of dipole moments 1 . 2 × 10-30 cm and 2 . 4 × 10-30 cm are placed in two difference uniform electric fields of strengths 5 × 104 N C-1 and 15 × 104 N C-1 respectively. The ratio of maximum 1 torque experienced by the electric dipoles will be 𝑥. The value of 𝑥 is _____ .

Q26.The potential energy of a particle of mass 4 kg in motion along the x-axis is given by U = 4(1 −cos 4x) J. The time period of the particle for small oscillation (sin θ ≃θ) ( Kπ ) s. The value of K is _____ .

Q26.The first overtone frequency of an open organ pipe is equal to the fundamental frequency of a closed organ pipe. If the length of the closed organ pipe is 20 cm. The length of the open organ pipe is _____ cm

Q26.A 10 Ω, 20 mH coil carrying constant current is connected to a battery of 20 V through a switch. Now after switch is opened current becomes zero in 100 μs. The average e.m.f. induced in the coil is _____ V.

Q26.For the network shown below, the value of VB −VA is _____ V . JEE Main 2022 (29 Jun Shift 1) JEE Main Previous Year Paper

Q26.A long cylindrical volume contains a uniformly distributed charge of density ρ C m−3 . The electric field inside the cylindrical volume at a distance x = 2ε0ρ m from its axis is _____ V m−1 . JEE Main 2022 (27 Jul Shift 1) JEE Main Previous Year Paper

Q26.A set of 20 tuning forks is arranged in a series of increasing frequencies. If each fork gives 4 beats with respect to the preceding fork and the frequency of the last fork is twice the frequency of the first, then the frequency of last fork is _____ Hz.