A liquid drop having surface energy ‘E’ is spread into 216 droplets of the same size. The final surface energy of the droplets is __.
Two spheres ‘S1’ and ‘S2’ have same radii but temperatures are ‘T1’ and ‘T2’ respectively. Their emissive power is same and emissivity is in the ratio 1 : 4. Then the ratio ‘T1’ to‘T2’ is
Two long parallel wires separated by distance ‘d’ carry currents I1 and I2 in the same direction. They exert a force F on each other. Now the current in one of the wire is increased to three times and its direction is made opposite. The distance between the wires is doubled. The magnitude of force between them is
In LCR series resonance circuit, choose the wrong statement
A light wave of wavelength ‘λ’ is incident on a slit of width ‘d’. The resulting diffraction pattern is observed on a screen at a distance ‘D’.If linear width of the principal maximum is equal to the width of the slit, then the distance D is
A diffraction pattern is obtained by making blue light incident on a narrow slit. If blue light is replaced by red light then
In a p-type semiconductor
A transistor is used as a common emitter amplifier with a load resistance 2 kΩ. The input resistance is 150 Ω. Base current is changed by 20 μA which results in a change in collector current by 1.5 mA. The voltage gain of the amplifier is
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
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
To a bird in air, a fish in water appears to be at 30 cm from the surface. If refractive index of water with respect to air is \(\frac {4}{3}\) ,the real distance of bird from the surface is
What is the density of water in kgdm–3 if its density in gcm–3 is 0.863?
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
In hydrogen atom, radius of the smallest orbit of the electron is a0, the radius of the third orbit is
Which one of the following statements is ‘NOT’ true about the angle of contact of a liquid?
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 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
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