Practice Questions

Q25.A person driving car at a constant speed of 15 m s-1 is approaching a vertical wall. The person notices a change of 40 Hz in the frequency of his car’s horn upon reflection from the wall. The frequency of horn is _______Hz . (Given: Speed of sound: 30 m s-1)

Q25.A block of mass 2 kg is attached with two identical springs of spring constant 20 N m-1 each. The block is placed on a frictionless surface and the ends of the springs are attached to rigid supports (see figure). When the mass is displaced from its equilibrium position, it executes a simple harmonic motion. The time period of oscillation is 𝜋 in SI unit. The value of 𝑋 is______. √𝑋 JEE Main 2023 (24 Jan Shift 1) JEE Main Previous Year Paper 𝑞

Q25.An electron revolves around an infinite cylindrical wire having uniform linear charge density 2 × 10-8 C m-1 in circular path under the influence of attractive electrostatic field as shown in the figure. The velocity of electron with which it is revolving is ______________ × 106 m s-1. Given mass of electron = 9 × 10-31 kg

Q26.A network of four resistances is connected to 9 V battery, as shown in figure. The magnitude of voltage difference between the points A and B is __________ V.

Q26.A stream of a positively charged particles having 𝑚= 2 × 1011 C kg-1 and velocity →v0 = 3 × 107 ^𝑖 m s-1 is deflected by an electric field 1 . 8 ^𝑗 kV m-1. The electric field exists in a region of 10 cm along 𝑥 direction. Due to the electric field, the deflection of the charge particles in the 𝑦 direction is _____ mm.

Q26.In an experiment to find emf of a cell using potentiometer, the length of null point for a cell of emf 1 . 5 V is found to be 60 cm. If this cell is replaced by another cell of emf 𝐸. the length-of null point increases by 𝑥 40 cm. The value of 𝐸 is V. The value of 𝑥 is ______. 10

Q26.Expression for an electric field is given by →𝐸= 4000 𝑥2 ^i V m-1. The electric flux through the cube of side 20 cm when placed in electric field (as shown in the figure) is ______ V cm. JEE Main 2023 (31 Jan Shift 1) JEE Main Previous Year Paper

Q26.In the circuit shown, the energy stored in the capacitor is 𝑛 μJ. The value of 𝑛 is _____.

Q26.As shown in the figure, a configuration of two equal point charges 𝑞0 = + 2𝜇C is placed on an inclined plane. Mass of each point charge is 20 g. Assume that there is no friction between charge and plane. For the system of two point charges to be in equilibrium (at rest) the height ℎ= 𝑥× 10-3 m. The value of 𝑥 is 1 Take = 9 × 109 N m2 C-2, 𝑔= 10 m s-2 4𝜋𝜀0 𝑥

Q26.A rectangular parallelopiped is measured as 1 cm × 1 cm × 100 cm. If its specific resistance is 3 × 10-7Ω m, then the resistance between its two opposite rectangular faces will be _____ × 10-7Ω.

Q26.As shown in the figure, a plane mirror is fixed at a height of 50 cm from the bottom of tank containing water (μ = 43 ). The height of water in the tank is 8 cm. A small bulb is placed at the bottom of the water tank. The distance of image of the bulb formed by mirror from the bottom of the tank is ______ cm.

Q26.As per the given figure, if d𝑡=d𝐼

Q26.A parallel plate capacitor with plate area 𝐴 and plate separation 𝑑 is filled with a dielectric material of dielectric constant 𝐾= 4 . The thickness of the dielectric material is 𝑥, where 𝑥< 𝑑. 2𝑑 𝑥= , respectively. If 𝐶1 = 2 μF, the value Let 𝐶1 and 𝐶2 be the capacitance of the system for 𝑥= 13𝑑 and 3 of 𝐶2 is _____ μF .

Q27.An object is placed on the principal axis of convex lens of focal length 10 cm as shown. A plane mirror is placed on the other side of lens at a distance of 20 cm. The image produced by the plane mirror is 5 cm inside the mirror. The distance of the object from the lens is ____ cm.

Q27.In the circuit diagram shown in figure given below, the current flowing through resistance 3 Ω is A. The 3 value of 𝑥 is ________. JEE Main 2023 (11 Apr Shift 1) JEE Main Previous Year Paper

Q27.The current required to be passed through a solenoid of 15 cm length and 60 turns in order to demagnetise a bar magnet of magnetic intensity 2 . 4 × 103 A m – 1 is ________ A.

Q27.Two identical cells, when connected either in parallel or in series gives same current in an external resistance 5 Ω. The internal resistance of each cell will be ______ Ω.

Q27.A beam of light consisting of two wavelengths 7000 A and 5500 A is used to obtain interference pattern in Young's double slit experiment. The distance between the slits is 2. 5 mm and the distance between the plane of slits and the screen is 150 cm. The least distance from the central fringe, where the bright fringes due to both the wavelengths coincide, is n × 10–5 m. The value of n is _____.

Q27.A hollow cylindrical conductor has length of 3 . 14 m, while its inner and outer diameters are 4 mm and 8 mm respectively. The resistance of the conductor is n × 10-3 𝛺. If the resistivity of the material is 2 . 4 × 10-8 𝛺 m. The value of n is _____.

Q27.A charge particle of 2 μC accelerated by a potential difference of 100 V enters a region of uniform magnetic field of magnitude 4 mT at right angle to the direction of field. The charge particle completes semicircle of radius 3 cm inside magnetic field. The mass of the charge particle is ______ × 10-18 kg.

Q27.The wavelength of the radiation emitted is λ0 when an electron jumps from the second excited state to the first excited state of hydrogen atom. If the electron jumps from the third excited state to the second orbit of the hydrogen atom, the wavelength of the radiation emitted will be 20 x λ0 . The value of x is________.

Q27.An electron in a hydrogen atom revolves around its nucleus with a speed of 6. 76 × 106 m s–1 in an orbit of radius 0. 52 Å. The magnetic field produced at the nucleus of the hydrogen atom is _______ T.

Q27.A straight wire carrying a current of 14 A is bent into a semicircular arc of radius 2 . 2 cm as shown in the figure. The magnetic field produced by the current at the centre 𝑂 of the arc is ____ × 10 – 4 T JEE Main 2023 (10 Apr Shift 2) JEE Main Previous Year Paper

Q27.The ratio of wavelength of spectral lines Hα and Hβ in the Balmer series is 20x . The value of x is _____.

Q27.In an experiment for estimating the value of focal length of converging mirror, image of an object placed at 40 cm from the pole of the mirror is formed at distance 120 cm from the pole of the mirror. These distances are measured with a modified scale in which there are 20 small divisions in 1 cm. The value of error in 1 measurement of focal length of the mirror is cm. The value of 𝐾 is ______. 𝐾