Practice Questions

Q27.As shown in the figure, a potentiometer wire of resistance 20 Ω and length 300 cm is connected with resistance box (R.B.) and a standard cell of emf 4 V. For a resistance '𝑅' of resistance box introduced into the circuit, the null point for a cell of 20 mV is found to be 60 cm. The value of '𝑅' is _____ Ω. 1

Q27.In the given circuit, the magnitude of VL and VC are twice that of VR . Given that f = 50 Hz , the inductance of the coil is 1 mH . The value of K is _____ . Kπ JEE Main 2022 (28 Jun Shift 2) JEE Main Previous Year Paper

Q27.In a coil of resistance 8 Ω, the magnetic flux due to an external magnetic field varies with time as 𝜙= 2 - 𝑡2 39 . The value of total heat produced in the coil, till the flux becomes zero, will be _____ J. JEE Main 2022 (26 Jul Shift 2) JEE Main Previous Year Paper

Q28.Two radioactive materials 𝐴 and 𝐵 have decay constants 25𝜆 and 16𝜆 respectively. If initially they have the 1 same number of nuclei, then the ratio of the number of nuclei of 𝐵 to that of A will be "𝑒" after a time 𝑎𝜆. The JEE Main 2022 (29 Jul Shift 2) JEE Main Previous Year Paper value of 𝑎 is _____ .

Q28.In Young's double slit experiment the two slits are 0. 6 mm distance apart. Interference pattern is observed on a screen at a distance 80 cm from the slits. The first dark fringe is observed on the screen directly opposite to one of the slits. The wavelength of light will be _____ nm.

Q28.A parallel beam of light is allowed to fall on a transparent spherical globe of diameter 30 cm and refractive index 1. 5 . The distance from the centre of the globe at which beam of light can converge is _____ mm. Q29. √d1 and √d2 are the impact parameters corresponding to scattering angles 60° and 90° respectively, when an α particle is approaching a gold nucleus. For d1 = xd2 , the value of x will be _____ .

Q28.A wire of length 314 cm carrying current of 14 A is bent to form a circle. The magnetic moment of the coil is A −m2 . [Given π = 3. 14]

Q28.The graph between 1 and 1 for a thin convex lens in order to determine its focal length is plotted as shown in u v the figure. The refractive index of lens is 1. 5 and its both the surfaces have same radius of curvatures R. The value of R will be _____ cm. (Where u = object distance, v = image distance)

Q28.In the given figure, the face 𝐴𝐶 of the equilateral prism is immersed in a liquid of refractive index 𝑛. For incident angle 60° at the side 𝐴𝐶, the refracted light beam just grazes along face 𝐴𝐶. The refractive index of √𝑥 the liquid 𝑛= . The value of 𝑥 is _____ . 4 (Given refractive index of glass = 1 . 5)

Q28.Eight copper wire of length 𝑙 and diameter d are joined in parallel to form a single composite conductor of resistance 𝑅. If a single copper wire of length 2𝑙 have the same resistance 𝑅 then its diameter will be _____ 𝑑.

Q28.Sodium light of wavelengths 650 nm and 655 nm is used to study diffraction at a single slit of aperture 0. 5 mm. The distance between the slit and the screen is 2. 0 m. The separation between the positions of the first maxima of diffraction pattern obtained in the two cases is _____ ×10−5 m

Q28.A singly ionized magnesium atom (A = 24) ion is accelerated to kinetic energy 5 keV, and is projected perpendicularly into a magnetic field B of the magnitude 0. 5 T. The radius of path formed will be _____ cm.

Q28.A sample contains 10−2 kg each of two substances A and B with half lives 4 s and 8 s respectively. The ratio of their atomic weights is 1 : 2 . The ratio of the amounts of A and B after 16 s is 100x . The value of x is _____ .

Q28.A light ray is incident, at an incident angle θ1 , on the system of two plane mirrors M1 and M2 having an inclination angle 75° between them (as shown in figure). After reflecting from mirror M1 it gets reflected back by the mirror M2 with an angle of reflection 30° . The total deviation of the ray will be _____ degree.

Q28.For the given circuit the current through battery of 6 V just after closing the switch ' S ' will be _____ A . ​

Q28.In the given figure of meter bridge experiment, the balancing length AC corresponding to null deflection of the galvanometer is 40 cm. The balancing length, if the radius of the wire AB is doubled, will be _____ cm. JEE Main 2022 (27 Jul Shift 2) JEE Main Previous Year Paper → +

Q28.A small bulb is placed at the bottom of a tank containing water to a depth of √7 m. The refractive index of water is 4 . The area of the surface of water through which light from the bulb can emerge out is xπ m2 . The 3 value of x is _____ .

Q28.A metallic rod of length 20 cm is placed in North-South direction and is moved at a constant speed of 20 m s−1 towards East. The horizontal component of the Earth's magnetic field at that place is 4 × 10−3 T and the angle of dip is 45°. The emf induced in the rod is _____ mV . JEE Main 2022 (27 Jun Shift 2) JEE Main Previous Year Paper

Q28.The length of a given cylindrical wire is increased to double of its original length. The percentage increase in the resistance of the wire will be _____ %

Q28.The frequencies at which the current amplitude in an LCR series circuit becomes times its maximum value, √2 are 212 rad s-1 and 232 rad s-1. The value of resistance in the circuit is 𝑅= 5 Ω. The self inductance in the circuit is _____ mH.

Q28.To light, a 50 W, 100 V lamp is connected, in series with a capacitor of capacitance 50 μF, with π√x 200 V, 50 Hz AC source. The value of x will be _____ .

Q28.A resistor develops 300 J of thermal energy in 15 s, when a current of 2 A is passed through it. If the current increases to 3 A, the energy developed in 10 s is _____ J.

Q29.A beam of monochromatic light is used to excite the electron in Li++ from the first orbit to the third orbit. The wavelength of monochromatic light is found to be x × 10−10 m. The value of x is _____ . [Given hc = 1242 eV nm]

Q29.Two beams of light having intensities I and 4I interfere to produce a fringe pattern on a screen. The phase difference between the two beams are π and π at points A and B respectively. The difference between the 2 3 resultant intensities at the two points is xI . The value of x will be _____ .

Q29.Two lighter nuclei combine to form a comparatively heavier nucleus by the relation given below: 2𝑋+1 2𝑋=1 4𝑌2 The binding energies per nucleon 2𝑋1 and 4𝑌2 are 1 . 1MeV and 7 . 6MeV respectively. The energy released in this process is_____ MeV.