Voltage divider circuits use resistors connected in series to a power supply to generate a range of output voltages. The voltage at the output (VT) is calculated using Ohm's law and depends on the values of the two resistors (R1 and R2) and the supply voltage (E). Under no load conditions, VT equals E*(R2/(R1+R2)). When a load is connected, VT remains approximately the same as long as the load current is much less than the divider current.

1. Voltage Divider Principle
Voltage divider circuits are used in electronics to supply a
range of voltages needed by a system from a single source.
The voltage divider uses the principles of Ohm’s law to
generate the necessary voltages.
VT = E
R2
R1 + R2
For good stability current I1 must be at least ten times that
flowing in the load.
IT
RLOAD
ILOADI1
R1
R2
VTE
+
-
VT no load conditions.
VT ~ E
R2
R1 + R2
VT loaded conditions ( ILOAD << I1 )

2. Voltage Divider Principle
Activity
Determine the voltage VT under no load conditions and when a
resistance of 2000 ohms in connected.
VT = E
R2
R1 + R2
For good stability current I1 must be at least ten times that
flowing in the load.
VT no load conditions.
VT ~ E
R2
R1 + R2
VT loaded conditions ( ILOAD << I1 )
IT
RLOAD
ILOADI1
R1
R2
VT
+
-
20VE
500Ω
500Ω

3. Divider Networks
Activity
1. For the potential divider circuit shown, use the voltage divider principle to
evaluate the voltage at VT a) when open circuit and b) when a load of 1000Ω
is connected as shown.
2. If the load resistance (RLOAD ) increased to 5kΩ what will be the effect on the
voltage VT .
3. Comment on your results
What is the effect on the voltage (VT ) supplied by the potential divider network
as the load (RLOAD )varies.
IT
RLOAD
ILOADI1
R1
450Ω
R2
300Ω
VT
+
-
25VE