JNTU question papers
JNTU B.Tech IV Semester Supplimentary Examinations, Feb 2008
SEM I- Conductors and magnetic materials
(Metallurgy & Material Technology)
1. Explain with suitable diagrams the conduction band, valence band and the forbidden band and explain the behavior of conductor, semi-conductor and insulator.
Explain the contribution of electrons and holes to electrical conduction.
2. (a) Explain the experimental setup for measuring Hall voltage.
(b) What are semi-condctors? How do they differ from conductors? Discuss. Explain about p-type semi-conductors.
3. (a) Write down as many as you can the ways in which n-type and p-type semiconductors differ from an intrinsic semi-conductor? Also explain it fully
(b) What do you mean by donor exhaustion? Discuss the donor exhaustion graphically in an impurity semi-conductor.
4. (a) Explain how electrons and holes both conduct in a pure silicon crystal. How is conductivity influenced by mobility of electrons and holes?
(b) What do you mean by ionic conductivity? How it differs from electronic conductivity? Explain the ionic conductivity in solids.
5. (a) What is super conductivity? Outline the experimental facts about this phenomenon.
(b) Explain about Meissner effect.
(c) Explain the important property changes that occur in materials when they change from normal to superconducting state.
6. (a) Explain why the ferromagnetic domains subdivide until they reach a certain minimum size.
(b) What form of domain reorientation dissipate the most energy? What part of the magnetization curve is produced by this effect? Explain.
7. (a) Explain the Neel’s theory of antiferromagnetism.
(b) Draw the B-H curve for a ferromagnetic material and explain it. Identify the retentivity and the coercive field on the curve. Explain the energy loss per cycle.
8. (a) Distinguish clearly between soft and hard magnetic materials. Discuss their important properties and applications.
(b) What magnetic characteristics are required for a soft magnet. What structural features optimize these behaviors. Discuss.