Practice Questions

Q25.If one wants to remove all the mass of the earth to infinity in order to break it up completely. The amount of GM energy that needs to be supplied will be x 2 where x is ________. R 5 (Round off to the Nearest Integer) ( M is the mass of earth, R is the radius of earth, G is the gravitational constant)

Q25.Two cars X and Y are approaching each other with velocities 36 km h−1 and 72 km h−1 respectively. The frequency of a whistle sound as emitted by a passenger in car X, heard by the passenger in car Y is 1320 Hz. If the velocity of sound in air is 340 ms−1, the actual frequency of the whistle sound produced is ________ Hz.

Q25.Consider two identical springs each of spring constant k and negligible mass compared to the mass M as shown. Fig. 1 shows one of them and Fig. 2 shows their series combination. The ratios of time period of oscillation of the two SHM is Tb = √x, where value of x is ______. Ta (Round off to the Nearest Integer)

Q25.The width of one of the two slits in a Young's double slit experiment is three times the other slit. If the amplitude of the light coming from a slit is proportional to the slit-width, the ratio of minimum to maximum intensity in the interference pattern is 𝑥: 4 where 𝑥 is _______ .

Q25.The electric field intensity is produced by the radiation coming from a 100 W bulb at a distance of 3 m is E . E . Where The electric field intensity produced by the radiation coming from 60 W at the same distance is √x5 the value of x =_________ . → 2 3 with E0 = 4. 0 × 103 N C−1. The flux of this

Q25.A common transistor radio set requires 12 V D . C . for its operation. The D . C . source is constructed by using a transformer and a rectifier circuit, which are operated at 220 V A . C . on standard domestic A . C . supply. The number of turns of secondary coil are 24, then the number of turns of primary are

Q25.The area of cross-section of a railway track is 0. 01 m2. The temperature variation is 10 °C. Coefficient of linear expansion of material of track is 10−5 ∘C−1. The energy stored per meter in the track is J m−1. (Young's modulus of material of track is 1011 N m−2 )

Q25.In the reported figure, heat energy absorbed by a system in going through a cyclic process is ______ πJ. JEE Main 2021 (20 Jul Shift 1) JEE Main Previous Year Paper

Q25.In the figure given, the electric current flowing through the 5 kΩ resistor is x mA . The value of x to the nearest integer is ________.

Q25.The percentage increase in the speed of transverse waves produced in a stretched string if the tension is increased by 4% , will be ___ % .

Q25.Two cars are approaching each other at an equal speed of 7. 2 km hr−1. When they see each other, both blow horns having a frequency of 676 Hz. The beat frequency heard by each driver will be _______ Hz. [Velocity of sound in air is 340 m s−1.

Q25.Two separate wires A and B are stretched by 2 mm and 4 mm respectively, when they are subjected to a force of 2 N. Assume that both the wires are made up of same material and the radius of wire B is 4 times that of the radius of wire A. The length of the wires A and B are in the ratio of a : b. Then ab can be expressed as x1 , where x is _____.

Q25.A galaxy is moving away from the earth at a speed of 286 km s−1 . The shift in the wavelength of a red line at 630 nm is x × 10−10 m. The value of x, to the nearest integer, is ___ . [Take the value of the speed of the light c, as 3 × 108 m s−1 ]

Q25.Time period of a simple pendulum is T . The time taken to complete 5 oscillations starting from mean position 8 is α T . The value of α is ______ . 12 JEE Main 2021 (26 Feb Shift 2) JEE Main Previous Year Paper Q26. 27 similar drops of mercury are maintained at 10 V each. All these spherical drops combine into a single big drop. The potential energy of the bigger drop is ___________ times that of a smaller drop.

Q25.Two travelling waves produces a standing wave represented by equation. y = (1. 0 mm) cos[(1. 57 cm−1)x] sin[(78. 5 s−1) t]. The node closest to the origin in the region x > 0 will be at x =. . . . . . (in cm).

Q25.The electric field in a region is given by E = ( 5 E0ˆi + 5 E0ˆj) through the rectangular surface of area 0. 2 m2 (parallel to y −z plane) to that of the surface of area 0. 3 m2 (parallel to x −z plane) is a : b = a : 2, where a =? [Here ˆi, ˆj and ˆk are unit vectors along x, y and z -axes respectively] Q26. 512 identical drops of mercury are charged to a potential of 2 V each. The drops are joined to form a single drop. The potential of this drop is V in Volt.

Q25.The mass per unit length of a uniform wire is 0. 135 g cm−1 . A transverse wave of the form y = −0. 21 sin(x + 30t) is produced in it, where x is in meter and t is in second. Then, the expected value of tension in the wire is x × 10−2 N . Value of x is (Round-off to the nearest integer)

Q25.In the given figure switches S1 and S2 are in open condition. The resistance across ab when the switches S1 and S2 are closed is ________ Ω.

Q25.Two circuits are shown in figure (a) and (b). At a frequency of _______ rad s−1 the average power dissipated in one cycle will be the same in both the circuits.

Q26.At very high frequencies, the effective impedance of the given circuit will be _________Ω .

Q26.For the circuit shown, the value of current at time t = 3. 2 s will be ______ A . JEE Main 2021 (27 Jul Shift 2) JEE Main Previous Year Paper [Voltage distribution V(t) is shown by Fig. (1) and the circuit is shown in Fig. (2)]

Q26.An electric bulb rated as 200 W at 100 V is used in a circuit having 200 V supply. The resistance 𝑅 that must be put in series with the bulb so that the bulb delivers the same power is ______ Ω.

Q26.A source and a detector move away from each other in absence of wind with a speed of 20 m s−1 , with respect to the ground. If the detector detects a frequency of 1800 Hz of the sound coming from the source, then the original frequency of source considering the speed of sound in the air 340 m s−1 will be _____ Hz .

Q26.A particle of mass 9. 1 × 10−31 kg travels in a medium with a speed of 106 m s−1 and a photon of radiation of linear momentum 10−27 kg m s−1 travels in a vacuum. The wavelength of the photon is ____ times the wavelength of the particle. ∘

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.