An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be
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A boat takes 2 h to travel 8 km and back in still water, the velocity of water 4 km/h, the time taken for goir up stream 8 km and coming track is
A body of mass 2 kg is rotating on a circular path of radius 0.8 m with an angular velocity 44 rac sec. If radius of path becomes 1 m then value t angular velocity will be
The string of a pendulum is horizontal. The mass of bob attached to it is m. Now, the string is released. The tension in the string in the lowest position is
An observer moves towards a stationary source of sound with a speed l/5th of the speed of sound. The wavelength and frequency of the source emitted by any source be λ, and f respectively. The apparent frequency and wavelength recorded by the observer are respectively -
Two similar springs P and Q have spring constants Kp and Kq , such that Kp > KQ. They are stretched, first by the same amount (case a), then by the same force (case b). The work done by the springs Wp and WQ are related as, in case (a) and case (b), respectively
A heater of 220 V heats a volume of water in 5 minutes. A heater of 110 V heats the same volume of water in
A circular road of radius 1000 m has banking angle 45°. The maximum safe speed of a car having mass 200 kg will be, if the coefficient of friction between tyre and road is 0.5
According to Einstein’s photoelectric equation, the plot of the kinetic energy of the emittec photoelectrons from a metal vs the frequency of the incident radiation gives a straight line whose slope
A black body calorimeter filled with hot water cools from 60°C to 50°C in 4 min and 40°C to 30°C in 8 min. The approximate temperature of surrounding is
In a nuclear fission, 0.1% mass is converted into energy. The energy released by the fission of 1 kg mass will be
The electric current in a circuit is given by I = 3t
Here, t is in second, I is in ampere. The rms current for the period t = 0 to t = 1 s is
A projectile is thrown in the upward direction making an angle of 60° with the horizontal direction, with a velocity of 147 ms-1. Then the time after which inclination with the horizontal is 45°, is
Pressure versus temperature graph of an ideal gas is as shown in figure. Corresponding density (p versus volume (V) graph will be
A tin nucleus (atomic number Z = 50) has a radius of 6.6 x 10-15 m. The potential on its surface will be (the charge on the proton = 1.6 x 10-19 C)
Velocity of sound in the atmosphere of a planet is 500 ms-1. The minium distance between the source of sound and the obstacle to hear the echo should be
Two rods of the same length and areas of cross section A1 and A2 have their ends at the same temperature K1 and K2 are the thermal conductivities of the two rods. The rate of flow of heat is same in both rods if
The electric charge on drop B is 1.6 x l0-19C and its mass is 1.6 x 10-14 kg. If the drop is in equilibrium, then the potential difference between the plates will be (where, density d = 10 x 10-3 kgm-3)
A cylindrical resonance tube, open at both ends has a fundamental frequency f in air, If half of the length is dipped vertically in water, the fundamental frequency of the air column will be
Twenty identical bulbs are connected in series across a 220 V supply. Two of the bulbs are found to bum out. The remaining 18 bulbs are connected again in series across the same supply. The illumination will be
The kinetic energy of a body becomes four times its inital value. The new momentum will be
The coefficients of self-induction of two coils are L1 ant L2. To induce an emf of 25 V in the coils change of current of 1A has to be produced in 5s and 50 ms respectively. The ratio of their self-inductances L1: L2 will be
The voltage time (V-t) graph for triangular wave having peak value V0 is as shown in figure. The rms value of V in time interval from t = 0 to T/4 is then find the value of x.
The speed of electromagnetic waves in a vacuum, is given by
A 2 kg copper block is heated to 500°C and then it is placed on a large block of ice at 0°C. If the specific heat capacity of copper is 400 J/kg°C and latent heat of fusion of water is 3.5 x 105 J/kg, the amount of ice that can melt is
Two coherent monochromatic light beams of intensities I and 4I are superposed. The maximum and minimum possible intensities in the resulting beam are
A current of I ampere flows in a wire forming a circular are of radius r meters subtending an angle θ at the cintre as shown. The magnetic field at the centre O in tesla is