Consider an electron in front of metallic surface at a distance d(treated as an infinite plane surface). Assume the force of attraction by the plate is given as `1/4 q^2/(4piepsilon_0d^2)`
Calculate work in taking the charge to an infinte distance from the plate. taking d=0.1nm, find the work done in electron volts. [such a force law is not valid for d< 0.1nm].

Two point electric charges of value q and 2q are kept at a distance d apart from each other in air. A third charge Q is to be kept along the same line in such a way that the net force action on q and 2q is zero. Calculate the position of charge Q in terms of q and d.

Two fixed identical conducting plates (alpha and beta) , each of surface areas S are charged to -Q and q, respectively, where Q>q>0. A third identical plate (y), free to move is located on the other side of the plate which charge q at a distance d. The third platea in released and colides with the plate beta . Assume the collision is elastic and the time of collision is sufficient to redistribute charge amongest beta and gamma . Find the electric field acting on the plate gamma before collision.

Answer carefully: Two large conducting spheres carrying charges Q_1 and Q_2 are brought close to each other. Is the magnitude of electrostatic force between them exactly given by ((Q_1 Q_2 )//(4piepsilon_0r^2)) , where r is the distance between their centres?

Assume that the de Broglie wave associated with an electron can from a standing wave between the atom arrange in a one dimensional array with nodes at each of the atomic sites. It is found that one such standing wave if the distance d between the atoms of the array is 2 A^0 A similar standing wave is again formed if d is increased to 2.5overset @A . Find the energy of the electrons in electron volts and the least value of d for which the standing wave type described above can from .

Two identical plane metallic surfaces A and B are kept parallel to each other in air separated by a distance of 1.09 cm as shown in Fig. HQ 6. Surface A is given a positive Potential of 10 V and outer surface of B is earthed. What is the work done in moving a charge of 20 muC from point X to Y. Where X is situated on surface A?

Two fixed identical conducting plates (alpha and beta) , each of surface areas S are charged to -Q and q, respectively, where Q>q>0. A third identical plate (y), free to move is located on the other side of the plate which charge q at a distance d. The third platea in released and colides with the plate beta . Assume the collision is elastic and the time of collision is sufficient to redistribute charge amongest beta and gamma . Find the charges on beta and gamma after the collision.

Consider a 20 W bulb emitting light of wavelength 5000 oversetcircA and shining on a metal surface kept at a distance 2m . Assume that the metal surface work function of 2eV and that each atom on the metal surface can be treated as a cirular disc of radius 1.5 A. will there be photoelectric emission?

Consider a 20 W bulb emitting light of wavelength 5000 oversetcircA and shining on a metal surface kept at a distance 2m . Assume that the metal surface work function of 2eV and that each atom on the metal surface can be treated as a cirular disc of radius 1.5 A. Estimate no. of photons emitted by the bulb per second.[Assume no other losses]

Consider a 20 W bulb emitting light of wavelength 5000 oversetcircA and shining on a metal surface kept at a distance 2m . Assume that the metal surface work function of 2eV and that each atom on the metal surface can be treated as a cirular disc of radius 1.5 A. Can you explain how photoelectric effect was observed instantaneously?