### Anna University - Electronic Device and Circuits (EDC) - May / June 2010 - Solved Two Marks

B.E/B.Tech Degree Examination, May/June 2010
• 3rd Semester EEE
Electronics Devices and Circuits
(2008 Regulations)

Two Marks with Answers for May / June 2010 Question Paper:

1. Define diffusion current.

There may exist an additional current due to the transport of charge in a semiconductor. Such an additional current is due o the phenomenon called diffusion. The current due to the diffusion is called diffusion current.

2. What are the applications of LED?

* All kinds of displays,
* in the optical devices such as opto coupler.
* As on-off indicator
* In remote controls andapplication like burglar alarm.

3. What is the relation IE ,IC ,and IB in CB configuration?

IE=IC+IB

IE=IC                      IC=IB

(since IB is negligible in CB)

4. Why are power transistor provided with heat sinks?

A thermal heat sink is usually used to draw heat from the device via thermal conductor which expels the heat into the ambient air via thermal cdnvection and heat radiation.

5. What is MOSFET? What are the types of MOSFET?

MOSFET: Metal oxide semiconductor field effect transistor It is a second category of field effect transistor.
Types:
* Depletion MOSFET (D-MOSFET) * Enhancement MOSFET (E-MQSFET)

6.Compare JFET and BJT:

7.Write the essential conditions for maintaining oscillations?

The two essential conditions for maintaining oscillations are called Barkhausen creiterion. .
1.The total phase shift around loop must be 0 degree or 360 degree.
2. The product of open loop gain(β) and feedback factor (β) i.e |Aβ| = 1

8.What do you understand by feed back in amplifier?

A small portion of output is fed back to input is called feedback.
When I/P and part of O/P in phase the feedback is positive feedback. When it is in out of phas, is called negative feedback.

9. Draw a simple integrating circuit.

10. What is called as clipper circuits?

The circuits which are used to clip off unwanted portion of the waveform, without disturbing the remaining part of the waveform are called clipper circuits or clippers.