BE Biotechnology Semester 1 (FE First Year) - University of Mumbai Important Questions for Applied Physics 1

In a solid the energy level is lying 0.012 eV below Fermi level. What is the probability of this level not being occupied by an electron 27℃?

Write the Fermi Dirac distribution function and terms in it. What is the probability of an electron being thermally excited to the conduction band in Si at 30 ℃. The band gap energy is 1.12 eV.  

With energy band diagram , explain the variation of fermi energy level with impurity concentration in extrinsic semiconductor. 

Show that fermi energy level in intrinsic semiconductor is at the Centre of forbidden energy gap. What is the probability of an electron being thermally excited to the conduction band in Si at 30℃. The band gap energy is 1.12 eV.

With energy band diagram ,explain the variation of fermi energy level with temperature in extrinsic semiconductor .

Calculate electron & hole concentration in intrinsic Si at room temperature if
its electrical conductivity is 4x10-4 mho/m.Given that mobility of electron=
0.14m2/V-sec and  mobility of holes=0.04m2/V-sec.

Show that for intrinsic semiconductors of the Fermi level lies midway between the conduction band and the valence band .With the help of diagram explain effect of impurity concentration on Fermi level of N type semiconductor.

Derive an expression for Hall voltage and Hall coefficient with neat labelled diagram.

What is the probability of an electron being thermally excited to conduction
band in Si at 27cC.The band gap energy is 1.12 eV.

Calculate conductivity of a germanium sample if a donar impurity atoms are added to the extent to one part in 10⁶  germanium atoms at room temperature.
Assume that only one electron of each atom takes part in conduction process.

Given:- Avogadro’s number = 6.023 × 10²³ atom/gm-mol . 
Atomic weight of Ge = 72.6

Mobility of electrons = 3800` (cm^2) / ( "volts") `sec

Density of Ge = 5.32 gm/ cm³

Discuss formation of copper pairs and energy gap in superconductor on the basis of BCS theory.

What is Maglev? How it can have very high speed?

Define the critical temperature. Slow that in the superconducting state the material is perfectly diamagnetic. 

What is working principle of SQUID ? Explain how it is used to detect the magnetic field?

What is the working principle of maglev? Explain how it can acquire high speed?

Explain Meissner Effect with the help of diagram.

Differentiate between Type-1 & Type- II Superconductors.

What is reverberation time? Discuss sabine formula. 

State any five factors affecting the acoustics of the building and give the remedies for each. 

Explain the factors on which reverberation time depends .