Rajasthan Technical University 2007-3rd Sem B.Tech Electronics and Communications Engineering Electronic Materials & Process, ,Back , - Question Paper
Electronic Materials & Process, RTU, 3rd semester Back Exam Paper,2007
Q1. (a) Describe the thermoelectric effects on conductivity of metals.
(b) A uniform wire has a resistivity of 1.54 x 108 ohm-m at room temperature for an electric field along the wire of 1 volt-cm-1. Compute average drift velocity of the electrons, assuming there are 5.8 x 10 28. Conduction electron per m3, calculate the mobility and relaxation time of the electrons [me =9.1 x 10-31 Kg, qe = 1.6 x 10-91 C].
Q2. (a) What do you understand by spontaneous polarization in a ferroelectric material? Explain Curie temperature applied to such a material.
(b) Explain the direct and indirect band gap in semiconductors used for electronic devices.
Q3. Write the difference between:
(i) soft and hard magnetic materials
(ii) Degenerative and non-degenerative semiconductors.
Q4. (a) Describe the advantages and limitations of surface mounting devices.
(b) explain the electrical properties of conductive materials.
Q5. (a) explain the printed circuit boards (PCBS) manufacturing process.
(b) explain the electroic properties of silicon material.
Q6. (a) what is superconductor? Explain its types and uses in practical field.
(b) a solenoid of 0.3 m length and 2 cm in diameter is required to develop magnetic field of 10KA/min vacuum when powered with 1A. How many turns of wire are required? If the solenoid is wound with 0.5mm diameter copper wire, what dc voltage is required to power it?
The resistivity of copper is 17.2 x 10-9 ohm-m.
Q7. (a) describe the classification of magnetic materials and its important salient features with application.
(b) a paramagnetic system of electric spin magnetic dipole moment is placed in an external field of 105 amp/m. calculate the average magnetic moment per dipole at 300K. Also calculate the fractional number of spins which are parallel to the field.
Q8. write short notes on the following:
(i) meissners effect
(ii) zone refining
| Earning: Approval pending. |
