Page 976 - Basic Electrical Engineering

or, I (1 − α ) = α I
dc B
dc
C
or,

or,
I = β I (v)
c
dc B
where

Beta dc (β ) is called the base to collector current gain. This is the ratio of
dc
I and I . The value of β varies from 25 to over 200.
dc
C
B
Example 14.2 An n–p–n transistor has been shown provided with biasing

voltage V and V . Calculate the values of I and I if α is 0.96 and I is
C
B
CB
BE
dc
E
80 μA. Also calculate the value of β .
dc

Figure 14.17 Relates to example 14.2

Solution:

6
Given α = 0.96, I = 80 × 10 A
dc
B