Practice Questions

Q24.Three capacitors of capacitances 25μF, 30μF and 45μF are connected in parallel to a supply of 100 V . Energy stored in the above combination is E. When these capacitors are connected in series to the same supply, the stored energy is 9 E . The value of x is _____. x

Q24.A closed and an open organ pipe have same lengths. If the ratio of frequencies of their seventh overtones is ( a−1a ) then the value of a is ________ → 2^i+6^j+8^k 2^i+^j+^k . The

Q24.A simple harmonic oscillator has an amplitude A and time period 6π second. Assuming the oscillation starts from its mean position, the time required by it to travel from x = A to x = √32 A will be πx s, where x = _______.

Q24.A soap bubble is blown to a diameter of 7 cm.36960erg of work is done in blowing it further. If surface tension of soap solution is 40dyne/cm then the new radius is______ cm Take (π = 227 )

Q24.A particle is doing simple harmonic motion of amplitude 0.06 m and time period 3.14 s. The maximum velocity of the particle is _______ cm/s.

Q24.A mass 𝑚 is suspended from a spring of negligible mass and the system oscillates with a frequency 𝑓1 . The frequency of oscillations if a mass 9𝑚 is suspended from the same spring is 𝑓2 . The value of 𝑓1 is _____ . 𝑓2

Q24.An object of mass 0.2 kg executes simple harmonic motion along x axis with frequency of ( 25π )Hz. At the position x = 0.04 m the object has kinetic energy 0.5 J and potential energy 0.4 J. The amplitude of oscillation is _____ cm .

Q24.In a closed organ pipe, the frequency of fundamental note is 30 Hz. A certain amount of water is now poured in the organ pipe so that the fundamental frequency is increased to 110 Hz. If the organ pipe has a cross- sectional area of 2 cm2 , the amount of water poured in the organ tube is ________ g. (Take speed of sound in air is 330 m s−1 )

Q24.A simple pendulum is placed at a place where its distance from the earth's surface is equal to the radius of the earth. If the length of the string is 4 m, then the time period of small oscillations will be _________s. [take 𝑔= 𝜋2 m s-2]

Q24.A particle performs simple harmonic motion with amplitude 𝐴. Its speed is increased to three times at an 2𝐴 𝑛𝐴 instant when its displacement is . The new amplitude of motion is . The value of 𝑛 is _____. 3 3

Q24.The position, velocity and acceleration of a particle executing simple harmonic motion are found to have magnitudes of 4 m, 2 ms−1 and 16 ms−2 at a certain instant. The amplitude of the motion is √x, m where x is ________

Q24.When the displacement of a simple harmonic oscillator is one third of its amplitude, the ratio of total energy to the kinetic energy is x , where x =_________. 8

Q24.At room temperature (27∘C), the resistance of a heating element is 50Ω. The temperature coefficient of the material is 2.4 × 10−4∘C−1 . The temperature of the element, when its resistance is 62Ω, is _____ ∘C.

Q24.A closed organ pipe 150 cm long gives 7 beats per second with an open organ pipe of length 350 cm, both vibrating in fundamental mode. The velocity of sound is ______ m s-1.

Q24.A particle executes simple harmonic motion with an amplitude of 4 cm . At the mean position, velocity of the particle is 10 cm s−1 . The distance of the particle from the mean position when its speed becomes 5 cm s−1 is √α cm , where α =______. JEE Main 2024 (27 Jan Shift 1) JEE Main Previous Year Paper

Q24.A tuning fork resonates with a sonometer wire of length 1 m stretched with a tension of 6 N . When the tension in the wire is changed to 54 N, the same tuning fork produces 12 beats per second with it. The frequency of the tuning fork is _______ Hz .

Q24.The time period of simple harmonic motion of mass 𝑀 in the given figure is 𝜋√ 𝛼𝑀5𝐾, where the value of _______. JEE Main 2024 (31 Jan Shift 2) JEE Main Previous Year Paper

Q24.The displacement of a particle executing SHM is given by x = 10 sin (wt + π3 )m. The time period of motion is 3.14 s. The velocity of the particle at t = 0 is ______ m/s.

Q24.Two open organ pipes of lengths 60 cm and 90 cm resonate at 6th and 5th harmonics respectively. The difference of frequencies for the given modes is _______ Hz . (Velocity of sound in air = 333 m/s )

Q25.Three infinitely long charged thin sheets are placed as shown in figure. The magnitude of electric field at the point P is xσ . The value of x is _______ (all quantities are measured in SI units). ϵo JEE Main 2024 (06 Apr Shift 1) JEE Main Previous Year Paper

Q25.An electric field, E = √6 passes through the surface of 4 m2 area having unit vector ^n = ( √6 ) electric flux for that surface is ______ Vm .

Q25.A thin metallic wire having cross sectional area of 10−4 m2 is used to make a ring of radius 30 cm. A positive charge of 2π C is uniformly distributed over the ring, while another positive charge of 30 pC is kept at the centre of the ring. The tension in the ring is _______ N; provided that the ring does not get deformed (neglect the influence of gravity). (Given, 1 = 9 × 109 SI units) 4πϵ0

Q25.An electron is moving under the influence of the electric field of a uniformly charged infinite plane sheet S having surface charge density +σ. The electron at t = 0 is at a distance of 1 m from S and has a speed of 1 m s−1 . The maximum value of σ, if the electron strikes S at t = 1 s is α[ mϵ0e ] m2C . The value of α is _____.

Q25.A parallel plate capacitor with plate separation 5 mm is charged up by a battery. It is found that on introducing a dielectric sheet of thickness 2 mm, while keeping the battery connections intact, the capacitor draws 25% more charge from the battery than before. The dielectric constant of the sheet is ____.

Q25.A parallel plate capacitor of capacitance 12.5pF is charged by a battery connected between its plates to potential difference of 12.0 V. The battery is now disconnected and a dielectric slab (ϵr = 6) is inserted between the plates. The change in its potential energy after inserting the dielectric slab is _____ 10−12 J.