2073 Chaitra Regular
2073 Chaitra Regular electrical Engineering Material IOE Pulchowk
1. a) Define population density. Prove that Fermi energy in
metal is independent of temperature and depends only on its electron
concentration.[8]
b) Consider an Al-Cu thermocouple pair, Estimate the potential difference available from this thermo-couple if one junction is held at 0°C and other at 100°C.[4]
2. a) Explain how energy bands are formed in solids taking the example of N number of Lithium atoms for the explanation.[6]
b) Drift mobility of conduction electron is 43cm'v's and the mean speed is 1.2 10 ms. Calculate the mean free path of electrons between collisions.[4]
3. a) Show that dipolar polarization is a temperature-dependent parameter.[6]
b) Determine electronic polarizability due to valence electrons per Si-atoms. If the sample is supplied by a voltage on its electrode by how much is the local field great than the applied field? Take E = 11.9 and number of Si-atoms per um volume = 5*10ml[4]
4. a) Differentiate between ferrimagnetic and ferromagnetic materials.[6]
b) What is the Meissner effect? Differentiate between type I and type II superconductors material.[6]
5. a) Explain how donor dopants contribute electrons in the conduction band in the n-type extrinsic semiconductor. Also, prove that meanings where symbols have their use.[[6]
b) Describe the importance of determining Fermi energy in semiconductor materials.[6]
c) The density of states related to effective masses of electrons and holes in silicon am approximately 1.08, and 0.56, respectively. The electron and hole drift mobilities at room temperature are 1350 and 450 respectively Calculate intrinsic concentration and intrinsic resistivity of silicon. The energy bandgap for silicon is 1.1eV.[8]
6. a) An n-type semiconductor doped with 10 phosphorus atoms has been doped with 10 boron atoms. Calculate the electron and hole concentrations and conductivity.[6]
b) Explain bow does the temperature affects the formation of carrier concentration in a semiconductor?[6]
C) Differentiate between si and GaAs with their respective E-k curve.[6]
b) Consider an Al-Cu thermocouple pair, Estimate the potential difference available from this thermo-couple if one junction is held at 0°C and other at 100°C.[4]
2. a) Explain how energy bands are formed in solids taking the example of N number of Lithium atoms for the explanation.[6]
b) Drift mobility of conduction electron is 43cm'v's and the mean speed is 1.2 10 ms. Calculate the mean free path of electrons between collisions.[4]
3. a) Show that dipolar polarization is a temperature-dependent parameter.[6]
b) Determine electronic polarizability due to valence electrons per Si-atoms. If the sample is supplied by a voltage on its electrode by how much is the local field great than the applied field? Take E = 11.9 and number of Si-atoms per um volume = 5*10ml[4]
4. a) Differentiate between ferrimagnetic and ferromagnetic materials.[6]
b) What is the Meissner effect? Differentiate between type I and type II superconductors material.[6]
5. a) Explain how donor dopants contribute electrons in the conduction band in the n-type extrinsic semiconductor. Also, prove that meanings where symbols have their use.[[6]
b) Describe the importance of determining Fermi energy in semiconductor materials.[6]
c) The density of states related to effective masses of electrons and holes in silicon am approximately 1.08, and 0.56, respectively. The electron and hole drift mobilities at room temperature are 1350 and 450 respectively Calculate intrinsic concentration and intrinsic resistivity of silicon. The energy bandgap for silicon is 1.1eV.[8]
6. a) An n-type semiconductor doped with 10 phosphorus atoms has been doped with 10 boron atoms. Calculate the electron and hole concentrations and conductivity.[6]
b) Explain bow does the temperature affects the formation of carrier concentration in a semiconductor?[6]
C) Differentiate between si and GaAs with their respective E-k curve.[6]
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