# Electronic Devices and Circuits (EDC) : Tamilnadu Polytechnics One Mark Questions and Answers L Scheme

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Write the uses of opto coupler.
• It is used to couple digital or analog signals.
• It is used for interfacing different types of
• logic circuits.
• It is used for interfacing high level and low
• voltage systems
State the application of LDR.
• Used as ON-OFF switch.
• Used in object counters.
• Used to measure intensity of light
• Used in burglar alarms
What are the two types of LCD?
• Dynamic Scattering
• Field Effect
Define breakover voltage of SCR?
It is the maximum forward voltage gate being open, at which SCR starts conducting heavily is turned ON. Voltage range – 50 V to 500 V.

Define holding current of SCR?
It is the maximum anode current, gate being open at which SCR is turned OFF from ON condition.

Define the terms unipolar and bipolar?
The flow of current only depends upon the majority carriers (either electrons or holes). So that device is called Unipolar device.

Define drift current?
When an electric field is applied across the semiconductor materials, holes move towards the negative and electrons move towards the positive.  This effect of movement of charge carries constitutes a current known as ‘drift current’.
Define diffusion current?
When no electric field applied.  The charge carriers have the tendency to move from the higher concentration region to that of lower concentration region.  Now the movement of charge carriers produces a current known as ‘diffusion’.
Define peak inverse voltage?
It is the maximum allowable reverse voltage that can appear across the diode without causing it any damage range between 10V to 10 KV.

Ashock Kumar.,B.E
Lecturer/ECE
Karaikal Polytechnic College
Karaikal-609602

Emmanuel Paul Antony.S.,B.Tech
Lecturer/ECE
Karaikal Polytechnic CollegeKaraikal-609602