Practice Questions

Q23.Two concentric circular coils, C1 and C2 , are placed in the XY plane. C1 has 500turns, and a radius of 1 cm . C2 has 200 turns and radius of 20 cm . C2 carries a time dependent current I(t) = (5t2 −2t + 3)A where t is in s. The emf induced in C1(in mV) at the instant t = 1 s is x4 . The value of x is ..........

Q23.Four resistance 40 Ω, 60 Ω, 90 Ω 110 Ω and make the arms of a quadrilateral ABCD. Across AC is a battery of emf 40 V and internal resistance negligible. The potential difference across BD in V is __________

Q23. M grams of steam at 100oC is mixed with 200g of ice at its melting point in a thermally insulated container. If it produces liquid water at 40oC [heat of vaporization of water is 540cal/g and heat of fusion of ice is 80cal/g ], the value of M is ________

Q23.A wire of density 9 × 10–3 kg cm–3 is stretched between two clamps 1 m apart. The resulting strain in the wire is 4. 9 × 10–4 . The lowest frequency of the transverse vibrations in the wire (Young's modulus of wire Y = 9 × 1010 Nm–2 ), (to the nearest integer),_______

Q23.A one metre long (both ends open) organ pipe is kept in a gas that has double the density of air at STP. Assuming the speed of sound in air at STP is 300 m/s, the frequency difference between the fundamental and second harmonic of this pipe is __________ Hz. JEE Main 2020 (08 Jan Shift 1) JEE Main Previous Year Paper

Q23.A closed vessel contains 0.1 mole of a monoatomic ideal gas at 200 K. If 0.05 mole of the same gas at 400 K is added to it, the final equilibrium temperature (in K) of the gas in the vessel will be close to ______

Q23.Nitrogen gas is at 300 °C temperature. The temperature (in K ) at which the rms speed of a H2 molecule would be equal to the rms speed of a nitrogen molecule, is … … … . (Molar mass of N2 gas 28 g ).

Q23.Three containers C1, C2 and C3 have water at different temperatures. The table below shows the final temperature T when different amounts of water (given in liters) are taken from each container and mixed (assume no loss of heat during the process) JEE Main 2020 (08 Jan Shift 2) JEE Main Previous Year Paper C1 C2 C3 T 1l 2l −− 60oC −− 1l 2l 30oC 2l −− 1l 60oC 1l 1l 1l θ The value of θ (in oC to the nearest integer) is___________

Q23.In a meter bridge experiment S is a standard resistance. R is a resistance wire. It is found that balancing length is l = 25cm. If R is replaced by a wire of hall length and half diameter that of R of same material, then the JEE Main 2020 (09 Jan Shift 2) JEE Main Previous Year Paper balancing distance l' (in cm ) will now be ______________.

Q23.In a series LR circuit, power of 400 W is dissipated from a source of 250 V, 50 Hz. The power factor of the circuit is 0. 8 . In order to bring the power factor to unity, a capacitor of value C is added in series to the L and R. Taking the value of C as ( 3πn ) μF , then value of n is

Q23.When a long glass capillary tube of radius 0. 015 cm is dipped in a liquid, the liquid rises to a height of 15 cm within it. If the contact angle between the liquid and glass to close to 0°, the surface tension of the liquid, in milliNewton m−1, is [ρ(liqued) = 900 kg m−3, g = 10 m s−2] (Given answer in closed integer)

Q24.A prism of angle A = 1° μ = 1. 5 . A good estimate for the minimum angle of deviation (in degrees) is close to N . Value of N is … … … 10

Q24.Suppose that intensity of a laser is ( 315π ) W m−2. The rms electric field, in units of V m−1 associated with this source is close to the nearest integer is −(ε0 = 8. 86 × 10−12 C2 N m−2; c = 3 × 108 m s−1)

Q24.In a fluorescent lamp choke (a small transformer) 100V of reverse voltage is produced when the choke current changes uniformly from 0.25A to 0 in a duration of 0.025ms . The self-inductance of the choke (in mH ) is estimated to be ________

Q24.A galvanometer coil has 500 turns and each turn has an average area of 3 × 10−4m2 . If a torque of 1. 5 Nm is required to keep this coil parallel to a magnetic field when a current of 0. 5A is flowing through it, the strength of the field (in T) is _________ .

Q24.An ideal cell of emf 10V is connected in circuit shown in figure. Each resistance is 2Ω . The potential difference (in V ) across the capacitor when it is fully charged is _____________

Q24.A loop ABCDEFA of straight edges has six corner points A(0, 0, 0), B(5, 0, 0), C(5, 5, 0), D(0, 5, 0), E(0, 5, 5) and F(0, 0, 5) . The magnetic field in this region is → B = + ABCDEFA (in Wb ) is _____________ (3ˆi 4ˆk)T . The quantity of flux through the loop

Q24.A circular coil of radius 10 cm is placed in a uniform magnetic field of 3. 0 × 10−5 T with its plane perpendicular to the field initially. It is rotated at constant angular speed about an axis along the diameter of coil and perpendicular to magnetic field so that it undergoes half of rotation in 0. 2 s. The maximum value of EMF induced (in μV ) in the coil will be close to the integer....

Q24.The distance between an object and a screen is 100 cm. A lens can produce real image of the object on the screen for two different positions between the screen and the object. The distance between these two positions is 40 cm. If the power of the lens is close to ( 100N )D where N is an integer, the value of N is _________ JEE Main 2020 (04 Sep Shift 2) JEE Main Previous Year Paper

Q24.A 60pF capacitor is fully charged by a 20V supply. It is then disconnected from the supply and is connected to another uncharged 60pF capacitor in parallel. The electrostatic energy that is lost in this process by the time the charge is redistributed between them is (in nJ ) ________

Q24.A compound microscope consists of an objective lens of focal length 1 cm and an eye piece of focal length 5 cm with a separation of 10 cm. The distance between an object and the objective lens, at which the strain on the eye is minimum is 40n cm. The value of n is.......

Q24.Four resistances of 15 Ω, 12 Ω, 4 Ω and 10 Ω respectively in cyclic order to form Wheatstone’s network. The resistance that is to be connected in parallel with the resistance of 10 Ω to balance the network is ______________ Ω.

Q24.In a compound microscope, the magnified virtual image is formed at a distance of 25 cm from the eye-piece. The focal length of its objective lens is 1 cm . If the magnification is 100 and the tube length of the microscope is 20 cm, then the focal length of the eye-piece lens (in cm ) is ______

Q24.The series combination of two batteries, both of the same emf 10V, but different internal resistance of 20 Ω and 5 Ω, is connected to the parallel combination of two resistors 30 Ω and x Ω. The voltage difference across the battery of internal resistance 20 Ω is zero, the value of x (in Ω) is____ ∘

Q24.A Young's double-slit experiment is performed using monochromatic light of wavelength λ. The intensity of light at a point on the screen, where the path difference is λ, is K units. The intensity of light at a point where the path difference is λ is given by nK , where n is an integer. The value of n is 6 12