A wall is hit elastically and normally by ‘n’ balls per second. All the balls have the same mass ‘m’ and are moving with the same velocity ‘u’. the force exerted by the balls on the wall is
The ratio of the speed of sound in helium gas to that in nitrogen gas at same temperature is (γHe = \(\frac {5}{3}\), γN2 = 4 , M N2 =28)
For a particular sound wave propagating in air, a path difference between two points is 0.54 m which is equivalent to phase difference of (1.8 π)c. If the velocity of sound wave in air is 330 m/s, the frequency of this wave is
An equation of a simple harmonic progressive wave is given by y = A sin (100πt-3x).The distance between two particles having a phase difference of \(\frac {π}{3}\) in metre is
Two point charges q1 and q2 are ‘l’ distance apart. If one of the charges is doubled and distance between them is halved, the magnitude of force becomes n times, where n is
A metal disc of radius ‘R’ rotates with an angular velocity ‘ω’ about an axis perpendicular to its plane passing through its centre in a magnetic field of induction ‘B’ acting perpendicular to the plane of the disc. The induced e.m.f. between the rim and axis of the disc is (magnitude only)
If ‘N’ is the number of turns in a circular coil, the value of its self-inductance varies as
A diffraction pattern is obtained by making blue light incident on a narrow slit. If blue light is replaced by red light then
A mass tied to a string is whirled in a horizontal circular path with a constant angular velocity and its angular momentum is L. If the string is now halved, keeping angular velocity same, then the angular momentum will be
A satellite of mass ‘m’ is revolving around the earth of mass ‘M’ in an orbit of radius ‘r’. The angular momentum of the satellite about the centre of orbit will be
What is the density of water in kgdm–3 if its density in gcm–3 is 0.863?
A 4 kg mass and a 1 kg mass are moving with equal energies. The ratio of the magnitude of their linear momenta is
Three isolated metal spheres A, B, C have radius R, 2R, 3R respectively, and same charge Q. UA, UB and UC be the energy density just outside the surface of the spheres. The relation between UA, UB and UC is
In metre bridge experiment, null point is obtained at 20 cm from left end of the wire, when resistance X is balanced against another resistance Y (X < Y). To balance a resistance 4 X against Y, the new position of the null point from the same end will be
An electron jumps from the 4th orbit to the 2nd orbit of hydrogen atom. Given the Rydberg’s constant R = 107 m-1. The frequency in Hz of the emitted radiation is (c = 3x108 m/s)
A van is moving with a speed of 108 km/hr on a level road where the coefficient of friction between the tyres and the road is 0.5. For the safe driving of the van, the minimum radius of curvature of the road shall be (Acceleration due to gravity, g=10 m/s2)
The maximum speed of a particle in S.H.M. is V. The average speed is
A liquid drop having surface energy ‘E’ is spread into 216 droplets of the same size. The final surface energy of the droplets is __.
A galvanometer of resistance G has voltage range Vg. Resistance required to convert it to read voltage up to V is
A metal wire of density ‘ρ’ floats on water surface horizontally. If it is NOT to sink in water, then maximum radius of wire is (T = surface tension of water, g = gravitational acceleration)
A magnetizing field of 1000 A/m produces a magnetic flux of 2.4 x 10-5 Wb in an iron bar of cross-sectional area 0.3 cm2.The magnetic permeability of the iron bar in SI unit is
A hollow cylinder has a charge q coulomb within it. It ϕ is the electric flux associated with the curved surface B, the flux linked with the plane surface A will be