BJT

Question 1

THE BRAINS
OF ELECTRONICS

Answer 1

TRANSISTORS

Question 2

What was the electronic device of interest and development during 1904 to 1947?

Answer 2

Vacuum tube

Question 3

What year was the vacuum tube introduce?

Answer 3

1904

Question 4

Who introduced the vacuum tube?

Answer 4

J.A Fleming

Question 5

What year did the control grid was added?

Answer 5

1906

Question 6

What is the third element?

Answer 6

Control grid

Question 7

Who added the third element?

Answer 7

Lee De Frost

Question 8

The first amplifier

Answer 8

Triode

Question 9

What is the negative effects of vacuum tube?

Answer 9

They were indispensable but they were large, short lived and consumed a lot of power.

Question 10

What is the 1st computer?

Answer 10

ENIAC

Question 11

How many vacuum tubes were used in e n i a c?

Answer 11

18000

Question 12

What is the effect of overheating a vacuum tube?

Answer 12

black stain on the inside of the glass tube

Question 13

Meaning of eniac

Answer 13

Electronic Numerical Integrator and Computer),

Question 14

Who are the three engineers?

Answer 14

John Bardeen, William Shockley, and Walter Brattain

Question 15

what principle did the three engineers used?

Answer 15

amplifying an electrical current using a solid semiconducting material, silicon,

Question 16

When did The 3 demonstrated the amplifying action on the first transistor.

Answer 16

December 23, 1947,

Question 17

The advantages of transistor over the tube where immediately obvious:

Answer 17

It was smaller and light weight.  No heater requirement or heater loss.  Had rugged construction.  More efficient since less power was absorbed by the device itself
 It was instantly available for use, requiring no warm up period.
 Low operating voltages were possible.

Question 18

A Bipolar Junction
Transistor (BJT) is composed of

Answer 18

three terminals connected to three doped semiconductor regions.

Question 19

In an NPN transistor,a
thin and lightly doped
P-type material

Answer 19

is
sandwiched between two
thicker N-type materials.

Question 20

While a PNP transistor,
a thin and lightly doped
N-type material is

Answer 20

sandwiched between two
thicker P-type materials.

Question 21

The term bipolar reflects
the fact that

Answer 21

holes and
electrons participate in the
injection process into the
oppositely polarized
material.

Question 22

The basic operation of transistor will now be
described using the

Answer 22

NPN transistor.

Question 23

The figure shows the
proper bias arrangement
for NPN.

Notice that the
base-emitter junction

Answer 23

is
forward-biased

Question 24

The figure shows the
proper bias arrangement
for NPN.

Notice that the base-collector junction

Answer 24

reverse-biased.

Question 25

The figure shows the proper bias arrangement for PNP.\ Notice that the base-emitter junction

Answer 25

forward-biased

Question 26

The figure shows the proper bias arrangement for PNP. the base-collector junction is

Answer 26

reverse-biased.

Question 27

Notice that in both cases, the BE junction is

Answer 27

forward-biased

Question 28

Notice that in both cases,Notice that in both cases,

Answer 28

reverse-biased.

Question 29

What happens inside the NPN transistor?

Answer 29

The forward bias from base to emitter narrows the BE depletion region, and the reverse bias from base to collector widens the BC depletion region. The heavily doped n-type emitter region is teeming with conduction band (free) electrons that easily diffuse through the forward-biased BE junction into the p-type base region where they become minority carriers, just as in a forward-biased diode.

Question 30

NPN transistor The base region is lightly ______ and ______ so that it has a ________

Answer 30

doped, very thin, limited number of holes.

Question 31

The base region is lightly doped and very thin so that it has a limited number of holes. Thus,

Answer 31

only a small percentage of all the electrons flowing through the BE junction can combine with all the available holes in the base.

Question 32

These ______________, forming the

Answer 32

relatively few recombined electrons flow out of the base lead as valence electrons,small base electron current.

Question 33

Most of the electrons flowing from the emitter into the thin, lightly doped base region _________________

Answer 33

do not recombine but diffuse into the BC depletion region.

Question 34

Once in this region they are pulled through the _________by the electric field set up by the force of attraction ______

Answer 34

reverse-biased BC junction, between the positive and negative ions.

Question 35

The electrons now move through the _____, out through the __________ and into the

Answer 35

collector region,collector lead, positive terminal of the collector voltage source.

Question 36

Notice that the arrow on the emitter of the transistor symbols points in the

Answer 36

direction of the conventional current.

Question 37

These diagrams show that the emitter current (IE)

Answer 37

is the sum of the collector urrent and the base current

Question 38

IB is small compared to

Answer 38

IC and IE

Question 39

DC Beta,

Answer 39

The ratio of the DC collector current IC to the DC base current IB

Question 40

DC Beta,

Answer 40

current gain of a transistor.