EDC lab Viva Questions part-1 Basics

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1. What is the difference b/w Electronics and Electrical?
Electronics is the science which deals with the currents in semiconductor materials, Vacuum tubes.Where electrical deals with the currents in conductors                                                       

2.What are types of materials?                                    

conductors (Energy gap is zero)
semiconductors (Energy gap is narrower) (si 1.1ev,ge 0.7ev)
Insulators (energy gap is widest).

3.What are the Semiconductor and conductors?

Semiconductor which has 4 electrons in its valance band, and conductors has more than 4 electrons its valance band (best conductors: Ag,Al,Cu)

4. Difference b/w intrinsic and extrinsic Semiconductors?

Ans: intrinsic semiconductors are pure semiconductors, Extrinsic are impure, i.e.by adding impurities (tri, pentavalent)Extrinsic semiconductors created(P,N Type).

5.What are the type in Extrinsic semiconductors and how the formed?

P-Type and N-Type

by adding trivalentimpurities (arsenic, antimony, phosphorus) P-Type semiconductors created.by adding pentavalent impurities (aluminum, boron) N-Type semiconductors created.

6.What is Doping?

The processes of adding impurities.

7.How the PN Junction will be formed?

In a piece of semiconductor material, if one half is doped by P type impurity and the other half is doped by N type impurity

8.What is Barrier Potential (cut in voltage)?

The forward voltage at which the current through the junction starts increasing rapidly

9.What is Forward bias and Reverse bias?

In diode’s anode(P) voltage is more than cathode(N) voltage its forward bias, if anode voltage is less than cathode voltage its reverse bias.

10.What is Diffusion and Drift currents?

Drift current depends on the electric field applied, if there is no electric field there is no drift current. Diffusion current occurs even though there is not an electric field applied to the semiconductor.

11.What is mean by 1n4007?

1n – single junction

400x-is indicates the voltage, current and power
4007    reverse voltage from 50v to 1000v, max forward current is 1A

12.What is the Diode current Equation?

I=Io(e^(V/nV_T⁾-1), Io-Reverse saturation current,n=1,ge,2 si

13.Define PIV(Peak inverse voltage)?

It is the maximum reverse voltage that can be applied to the Diode. if the voltage across the junction exceeds PIV, under reverse bias condition, the junction gets damaged.

14.Define Reverse saturation current?

It is the current due to the diffusive flow of minority electrons from p- side to N- side, and minority holes from N- side to P- side

15.How do we test a diode using a multimeter?

Connect anode of dide to + terminal of multimeter and cathode to Negative terminal if voltage is 0.3 to 0.7 then diode is good.

16.Explain the capacitive effects in a junction.

Diffusion capacitance occurs in Forward bias, Transition capacitance exist in Reverse Bias.

17.What is mean by Break down, difference b/w avalanche Break down and Zener Break down?

Avalanche breakdown occurs in PN diode due to impact ionization of electron-hole pair, zener braek down occurs in Zener dioade due to electron hole pair break due to reverse bias voltage

18.What is the temperature effect on reverse saturation current and barrier voltage?

Reverse saturation doubles for every 10 degrees increment in temperature

Barrier voltage decreases by 2.5mv for every 1 degree increment in temperature

19.What is mean by static and dynamic resistances?

Static resistance is the ratio of V,I at operating (Q) point, dynamic resistance is inverse to the slope of the forward bias characteristics curve at operating point.

20.What are the PN Diode, Zener diode applications?

PN:rectifier,switch,clipper,clapper

Zener Diode:voltage regulator

21.Difference b/w PN, Zener Diode?

Pn is lightly doped, Zener heavily doped

22.Why is a Zener diode generally not connected in forward bias?

Zener gives the same response as pn diode in forward bias, so it uses in reverse bias only with Zener break down

23.What is the effect of Temperature on Zener diode?

For Vz(Break down voltage) less than 6v Vz is inversely proportional to temperature,For Vz(Break down voltage) more than 6v Vz is directly proportional to temperature.
24. Why silicon is more preferred than germanium?

For Si break Down voltage Is more than Ge, reverse saturation current Is less in Si,  Si is cheap (raw material Is sand)