Electronics

Question 1

Describe silicon electron shells

Answer 1

• Tetravalent (4 electrons)

Question 2

Describe Boron electron shells

Answer 2

• Trivalent ( 3 electrons)
• Acceptor
• P type

Question 3

B

Describe Phosphorus electron shells

Answer 3

• Pentavalent ( 5 electrons)
• A donor
• N type

Question 4

What is intrinsic conduction?

Answer 4

Conduction in pure silicon

Question 4

What is covalent bonding?

Answer 4

Electrons shared between 2 atoms

Question 5

Dessc

Describe Recombination..

Answer 5

Electron loses energy & drops back into to valence shell

Recombines the electron & hole

Question 6

What is doping?

Answer 6

Addition of N type or P type material to alter properties

Question 7

Describe Extrinsic conduction…

Answer 7

Conduction in doped semi-conductor due to adding N type or P type

Question 8

Describe a PN Junction diode

Answer 8

• No movement of electrons through depeltion zone till it gets 0.6v
• Recombination in depletion zone

Question 9

What is commutation?

Answer 9

When thryistor stops conducting

Question 10

What is the holding current in a thyristor?

Answer 10

The minimum current needed to continue conducting

Question 11

What are the components AC voltage goes through in a PSU?

Answer 11

1. Transformer
2. Rectifier (AC-DC)
3. Smoothing
4. Regulator ( controls V)

Question 12

When calculating an amplifier circuit what first should you do?

Answer 12

Minus 0.6v from voltage

Question 13

Transistor off =?

Answer 13

V High

Question 14

Transitor on =?

Answer 14

V 0

Question 15

When calculating resistance in a zener diagram what must you do?

Answer 15

Minus V over Zener from total V to find R