Biomedical Engineering Reference
In-Depth Information
Accordingly,
5
R
EQ
¼
5
4
¼
I
¼
1
:
25 A
and
p
¼
5
I
¼
6
:
25 W
9.4.5 Voltage and Current Divider Rules
Let us now extend the concept of equivalent resistance,
R
EQ
¼
V
I
, to allow us to quickly
calculate voltages in series resistor circuits and currents in parallel resistor circuits without
digressing to the fundamentals.
Voltage Divider Rule
The voltage divider rule allows us to easily calculate the voltage across a given resistor in
a series circuit. Consider finding
V
2
in the series circuit shown in Figure 9.18, where
R
EQ
¼
R
1
þ
R
2
. Accordingly,
I
¼
V
s
V
s
R
1
þ
R
2
R
EQ
¼
and therefore
R
2
V
¼
IR
¼
V
s
2
2
þ
R
R
1
2
This same analysis can be used to find
V
1
as
R
1
R
1
þ
R
2
¼
V
s
V
1
I
R
1
+
V
2
−
+
−
V
S
R
2
FIGURE 9.18
Voltage divider rule circuit.
