User Manual

(dividing throughout by R
L
and cancelling terms with R
L
as denominator)
As an example, assume
, , , and
Since the load resistance is large compared to the other resistances, the output
voltage V
L
will be approximately:
Due to the load resistance, however, it will actually be slightly lower: ≈ 6.623 V.
One of the advantages of the potential divider compared to a variable resistor in
series with the source is that, while variable resistors have a maximum resistance
where some current will always flow, dividers are able to vary the output voltage
from maximum (V
S
) to ground (zero volts) as the wiper moves from one end of the
potentiometer to the other. There is, however, always a small amount ofcontact
resistance.
In addition, the load resistance is often not known and therefore simply placing a
variable resistor in series with the load could have a negligible effect or an
excessive effect, depending on the load