Practice Questions

Q23.An oscillating LC circuit consists of a 75 mH inductor and a 1. 2 µF capacitor. If the maximum charge to the capacitor is 2. 7 µC. The maximum current in the circuit will be _______ mA.

Q23.A vessel of depth d is half filled with oil of refractive index n1 and the other half is filled with water of refractive index n2. The apparent depth of this vessel when viewed from above will be- (1) 2d(n1+n2) (2) d(n1+n2) n1+n2 2n1n2 (3) dn1n2 (4) dn1n2 2(n1+n2) (n1+n2)

Q23.Solid sphere 𝐴 is rotating about an axis 𝑃𝑄. If the radius of the sphere is 5 cm, then its radius of gyration about 𝑃𝑄 will be √𝑥 cm. The value of 𝑥 is _____.

Q23.Two identical solid spheres each of mass 2 kg and radii 10 cm are fixed at the ends of a light rod. The separation between the centres of the spheres is 40 cm . The moment of inertia of the system about an axis perpendicular to the rod passing through its middle point is______ × 10 – 3 kg m2 .

Q23.Figure below shows a liquid being pushed out of the tube by a piston having area of cross section 2 . 0 cm2. The area of cross section at the outlet is 10 mm2. If the piston is pushed at a speed of 4 cm s-1, the speed of outgoing fluid is _____ cm s-1

Q23.Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A : EM waves used for optical communication have longer wavelengths than that of microwave, employed in Radar technology. Reason R : Infrared EM waves are more energetic than microwaves, (used in Radar) In the light of given statements, choose the correct answer from the options given below. JEE Main 2023 (12 Apr Shift 1) JEE Main Previous Year Paper (1) Both A and R are true but R is NOT the correct (2) A is false but R is true explanation of A (3) A is true but R is false (4) Both A and R are true and R is the correct explanation of A

Q23.All electromagnetic wave is transporting energy in the negative z direction. At a certain point and certain time the direction of electric field of the wave is along positive y direction. What will be the direction of the magnetic field of the wave at that point and instant? JEE Main 2023 (25 Jan Shift 1) JEE Main Previous Year Paper (1) Positive direction of x (2) Positive direction of z (3) Negative direction of x (4) Negative direction of y

Q24.In a Young’s double slit experiment, the intensities at two points, for the path difference λ and λ ( λ being the 4 3 wavelength of light used) are I1 and I2 respectively. If I0 denotes the intensity produced by each one of the individual slits, then I1+I2 = ______ . I0

Q24.The fundamental frequency of vibration of a string between two rigid support is 50 Hz. The mass of the string is 18 g and its linear mass density is 20 g m−1 . The speed of the transverse waves so produced in the string is _______ m s–1 .

Q24.As shown in figures, three identical polaroids P1 , P2 and P3 are placed one after another. The pass axis of P2 and P3 are inclined at angle of 60º and 90º with respect to axis of P1 . The source S has an intensity of 256 W m−2 . The intensity of light at point O is _____ W m−2 . ∘

Q24.The energy density associated with electric field E and magnetic field B of an electromagnetic wave in free space is given by ( ε0− permittivity of free space, μ0− permeability of free space) (1) UE = 2ε0E2 , UB = 2μ0 B2 (2) UE = ε0E22 , UB = 2μ0B2 μ0B2 , UB = 2 (3) UE = ε0E22 , UB = μ0B22 (4) UE = 2ε0E2

Q24.A steel rod has a radius of 20 mm and a length of 2 . 0 m . A force of 62 . 8 kN stretches it along its length. Young's modulus of steel is 2 . 0 × 1011N m-2. The longitudinal strain produced in the wire is _________ × 10-5. JEE Main 2023 (06 Apr Shift 1) JEE Main Previous Year Paper

Q24.A capacitor of capacitance 900 µ F is charged by a 100 V battery. The capacitor is disconnected from the battery and connected to another uncharged identical capacitor such that one plate of uncharged capacitor connected to positive plate and another plate of uncharged capacitor connected to negative plate of the charged capacitor. The loss of energy in this process is measured as 𝑥× 10-2 J. The value of 𝑥 is ______.

Q24.A hole is drilled in a metal sheet. At 27 °C, the diameter of hole is 5 cm. When the sheet is heated to 177 °C, the change in the diameter of hole is 𝑑× 10-3 cm . The value of 𝑑 will be _____, if coefficient of linear expansion of the metal is 1 . 6 × 10-5 / ∘C

Q24.A scientist is observing a bacteria through a compound microscope. For better analysis and to improve its resolving power he should. (Select the best option) (1) Increase the wave length of the light (2) Increase the refractive index of the medium between the object and objective lens (3) Decrease the focal length of the eye piece (4) Decrease the diameter of the objective lens

Q24.The amplitude of a particle executing SHM is 3 cm. The displacement at which its kinetic energy will be 25% more than the potential energy is: ______ cm.

Q24.The length of a wire becomes 𝑙1 and 𝑙2 when 100 N and 120 N tension are applied respectively. If 1 10𝑙2 = 11𝑙1, then the natural length of wire will be 𝑥𝑙1. Here the value of 𝑥 is 𝜋

Q24.A transverse harmonic wave on a string is given by 𝑦𝑥, 𝑡= 5 sin6𝑡+ 0 . 003𝑥 where 𝑥 and 𝑦 are in cm and 𝑡 in sec. The wave velocity is _________ m s-1.

Q24.When a beam of white light is allowed to pass through convex lens parallel to principal axis, the different colours of light converge at different point on the principle axis after refraction. This is called : (1) Scattering (2) Chromatic aberration (3) Spherical aberration (4) Polarisation

Q24.In an experiment with sonometer when a mass of 180 g is attached to the string, it vibrates with fundamental frequency of 30 Hz. When a mass 𝑚 is attached, the string vibrates with fundamental frequency of 50 Hz. The value of 𝑚 is ______ g.

Q24.An ice cube has a bubble inside. When viewed from one side the apparent distance of the bubble is 12 cm . When viewed from the opposite side, the apparent distance of the bubble is observed as 4 cm . If the side of the ice cube is 24 cm , the refractive index of the ice cube is (1) 3 (2) 2 2 3 (3) 6 (4) 4 5 3

Q24.Two transparent media having refractive indices 1. 0 and 1. 5 are separated by a spherical refracting surface of radius of curvature 30 cm. The centre of curvature of surface is towards denser medium and a point object is placed on the principal axis in rarer medium at a distance of 15 cm from the pole of the surface. The distance of image from the pole of the surface is cm.

Q24.A ray of light is incident from air on a glass plate having thickness √3 cm and refractive index √2 . The angle of incidence of a ray is equal to the critical angle for glass-air interface. The lateral displacement of the ray when it passes through the plate is ____ × 10−2 cm . (given sin 15°= 0. 26 )

Q24.A rectangular block of mass 5 kg attached to a horizontal spiral spring executes simple harmonic motion of amplitude 1 m and time period 3 . 14 s. The maximum force exerted by spring on block is ___ N.

Q24.In a reflecting telescope, a secondary mirror is used to: (1) reduce the problem of mechanical support (2) make chromatic aberration zero (3) move the eyepiece outside the telescopic tube (4) remove spherical aberration