Practice Questions

Q26.A capacitor of 50μF is connected in a circuit as shown in figure. The charge on the upper plate of the capacitor is _________ μC.

Q26.The ratio of the equivalent resistance of the network (shown in figure) between the points a and b when switch is open and switch is closed is x : 8 . The value of x is JEE Main 2021 (27 Aug Shift 2) JEE Main Previous Year Paper

Q26.A particle performs simple harmonic motion with a period of 2 second. The time taken by the particle to cover a displacement equal to half of its amplitude from the mean position is 1 s. The value of a to the nearest a integer is

Q26.Four identical rectangular plates with length, l = 2 cm and breadth, b = 32 cm are arranged as shown in figure. The equivalent capacitance between A and C is xε0d . The value of x is _______. (Round off to the Nearest Integer)

Q26.The peak electric field produced by the radiation coming from the 8 W bulb at a distance of 10 m is x V m−1 . The efficiency of the bulb is 10% and it is a point source. The value of x is, 10 √μ0cπ

Q27.A uniform conducting wire of length is 24a, and resistance R is wound up as a current carrying coil in the shape of an equilateral triangle of side a and then in the form of a square of side a . The coil is connected to a voltage source V0. The ratio of magnetic moment of the coils in case of equilateral triangle to that for square is 1 : √y where y is ____________. + A . The R.M.S. value of this current is

Q27.A certain metallic surface is illuminated by monochromatic radiation of wavelength λ . The stopping potential for photoelectric current for this radiation is 3 V 0. If the same surface is illuminated with a radiation of wavelength 2λ, the stopping potential is V0. The threshold wavelength of this surface for photoelectric effect is___________ λ.

Q27.In a series LCR resonant circuit, the quality factor is measured as 100 . If the inductance is increased by two fold and resistance is decreased by two fold, then the quality factor after this change will be _______

Q27.In the given figure the magnetic flux through the loop increases according to the relation ϕB(t) = 10t2 + 20t , where ϕB is in milliwebers and t is in seconds. The magnitude of current through R = 2 Ω resistor at t = 5 s is _____ mA.

Q27.The value of aluminium susceptibility is 2 . 2 × 10-5. The percentage increase in the magnetic field if space 𝑥 within a current carrying toroid is filled with aluminium is 104. Then the value of 𝑥 is

Q27.From the given data, the amount of energy required to break the nucleus of aluminium 2713Al is __________ x × 10−3 J Mass of neutron = 1. 00866 u Mass of proton = 1. 00726 u Mass of Aluminium nucleus = 27. 18846 u (Assume 1 u corresponds to x J of energy) (Round off to the nearest integer) of its initial value in 30 years. The half-life of

Q27.Cross-section view of a prism is the equilateral triangle 𝐴𝐵𝐶 shown in the figure. The minimum deviation is observed using this prism when the angle of incidence is equal to the prism angle. The time taken by light to travel from 𝑃 (midpoint of 𝐵𝐶) to 𝐴 is ___________ × 10-10 s . (Given, speed of light in vacuum √3 = 3 × 108 m s-1 and cos30° = ) 2

Q27.A circular coil of radius 8. 0 cm and 20 turns is rotated about its vertical diameter with an angular speed of 50 rad s−1 in a uniform horizontal magnetic field of 3. 0 × 10−2 T . The maximum emf induced in the coil will be _______ ×10−2 volt (rounded off to the nearest integer).

Q27.Two small spheres each of mass 10 mg are suspended from a point by threads 0. 5 m long. They are equally charged and repel each other to a distance of 0. 20 m. The charge on each of the sphere is 21a × 10−8 C. The value of a will be ___.[Given g = 10 m s−2 ]

Q27.The frequency of a car horn encountered a change from 400 Hz to 500 Hz . When the car approaches a vertical wall. If the speed of sound is 330 m s−1 . Then the speed of car is ___ km h−1 .

Q27.A parallel plate capacitor has plate area 100 m2 and plate separation of 10 m. The space between the plates is filled up to a thickness 5 m with a material of dielectric constant of 10 . The resultant capacitance of the system is x pF. The value of ε0 = 8. 85 × 10−12 F m−1 . The value of x to the nearest integer is ______.

Q27.A cylindrical wire of radius 0. 5 mm and conductivity 5 × 107 S m−1 is subjected to an electric field of 10 mV m−1. The expected value of current in the wire will be x3π mA. The value of x is _________.

Q27.The voltage drop across 15 Ω resistance in the given figure will be _______ V.

Q27.An electromagnetic wave of frequency 5GHz, is travelling in a medium whose relative electric permittivity and relative magnetic permeability both are 2 . Its velocity in this medium is _______ × 107 m s-1.

Q27.The total charge enclosed in an incremental volume of 2 × 10−9 m3 located at the origin is nC, if electric flux density of its field is found as D = e−x sin yˆi −e−x cosyˆj + 2zˆk C m−2

Q27.An AC circuit has an inductor and a resistor of resistance R in series, such that XL = 3R. Now, a capacitor is added in series such that XC = 2R. the ratio of the new power factor with the old power factor of the circuit is √5 : x. The value of x is

Q27.Consider a 72 cm long wire AB as shown in the figure. The galvanometer jockey is placed at P on AB at a distance x cm from A . The galvanometer shows zero deflection. JEE Main 2021 (18 Mar Shift 2) JEE Main Previous Year Paper The value of x, to the nearest integer, is

Q27.In the given circuit of potentiometer, the potential difference E across AB( 10 m length) is larger than E1 and E2 as well. For key K1 (closed), the jockey is adjusted to touch the wire at point J1 so that there is no deflection in the galvanometer. Now the first battery (E1) is replaced by second battery (E2) for working by making K1 open and K2 closed. The galvanometer gives then null deflection at J2 . The value of E1E2 is a2 , where a =_______ .

Q27.A steel rod with 𝑦= 2 . 0 × 1011 N m-2 and 𝛼= 10-5 ∘C of length 4 m and area of cross-section 10 cm2 is heated from 0°C to 400°C without being allowed to extend. The tension produced in the rod is JEE Main 2021 (01 Sep Shift 2) JEE Main Previous Year Paper 𝑥× 105 N where the value of 𝑥 is _________ .

Q27.A point source of light S , placed at a distance 60 cm infront of the centre of a plane mirror of width 50 cm, hangs vertically on a wall. A man walks infront of the mirror along a line parallel to the mirror at a distance 1. 2 m from it (see in the figure). The distance between the extreme points where he can see the image of the light source in the mirror is__ cm