Four identical condensers are connected in parallel and then in series equivalent capacitance in series to that in parallel combination 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
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 4 kg mass and a 1 kg mass are moving with equal energies. The ratio of the magnitude of their linear momenta 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)
Two coils P and S have a mutual inductance of 5 x 10-3 H. If the current in the coil, P is I = 10 sin (100 πt), then the maximum value of the e.m.f. induced in coil S 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 photon of energy ‘E’ ejects photoelectrons from a metal surface whose work function is W0. If this electron enters into uniform magnetic field of induction ‘B’ in a direction perpendicular to field and describes a circular path of radius‘r’, then radius is given by
A liquid drop having surface energy ‘E’ is spread into 216 droplets of the same size. The final surface energy of the droplets 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 satellites A and B rotate round a planet’s orbit having radius 4R and R respectively. If the speed of satellite A is 3 V then speed of satellite B is
Two thin lenses have a combined power of +9D. When they are separated by a distance of 20 cm, then their equivalent power becomes +27/5 D. Their individual power (in dioptre) is
In a p-type semiconductor
A diffraction pattern is obtained by making blue light incident on a narrow slit. If blue light is replaced by red light then
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
What is intensive property?
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
What is change in internal energy if a system gains xJ of heat and yJ work is done on it?
Air column in two identical tubes is vibrating. Tube A has one end closed and tube B has both ends open. Neglecting end correction, the ratio of the fundamental frequency of air column in tube A to that in tube B is
For a particle performing S.H.M. the equation $ \frac{d^2x}{dt^2} + \alpha x = 0 $. Then the time period of the motion will be:
Consider the following statements about interference of light. A – When crest of one wave coincides with crest of another wave at a point, this point is a point of destructive interference. B – Two coherent sources emit wave of same frequency with constant phase difference.Choose the correct option from the following.
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