Bredhurst Receiving and Transmitting Society

Syllabus Sections:-

Potential dividers

3d.1 Understand that two or more resistors can be arranged to act as a potential divider and apply the formula

The formula is :-    

Potential divider formula

In an earlier section of this course discussion was given regarding two resistors acting as a potential divider.

This diagram was shown to you :- If this is new to you please look back to the earlier section.

However a potential divider can be two or more resistors but what ever number it is the resultant formula would be

as we would have to do separate calculation to end up with two resistors.

Looking at the diagram,

you can see that the output is leaving the potential divider of R1, Ra and Rb at the link between R1 and Ra.

With Ra and Rb are in series we can simply add together their values and come up with R2. This R2 we can use in the formula ................. simple eh ??

The V_out is thus dependent upon :-

• V_in

• R1

• R2

Example if Volts in are 12V  R1 = 10 ohms and R2 = 30 ohms then

Vout= 12 x 30/(10 + 30)

Vout = 12 x 0.75

Vout = 9V