2074 Ashwin EEM

2074 Ashwin Back

2074 Ashwin Back Electrical Engineering Material IOE Pulchowk

1. a) Explain the importance of quantum mechanics.  Differentiate between classical and

quantum mechanics with suitable examples.

 b) In the photoelectric experiment, green light. with a wavelength  of  522 nm is the

longest wavelength radiation that can cause photoemission of an electron from a clean

sodium surface.  Calculate the work function of sodium.  If ultraviolet radiation with a wavelength of 250 nm is incident to the sodium surface. What will be the kinetic energy of the photon-emitted electrons?

 a) what happens when the inter-atomic separation between the two helium atoms is very less?

Describe on the basis of the formation of bonding and antibonding molecular orbital.

a) Define the Local electric field and derive Clausius-massotti equation.

b) the number of electrons per unit volume of Silicon is 6xl022cm-3cm.  Calculate:

i)  Electronic polarizability),  due to valence electrons per silicon atom.

ii)  If the silicon crystal sample is an electrode on opposite faces, by how many, times the local field is greater then the applied field.

a) what is a domain wall? How does a domain wall, motion occur?

b) Explain the applications of soft magnetic materials.