Potential Divider Principle

potenial divider principle

By increasing the resistance of R1 or decreasing the resistance of R2, the Vout will be increased.

Sometimes, R1 or R2 are replaced by thermistors or light-dependent resistors (LDR)

  • Thermistors’s resistance normally decreases as temperature increases.
  • LDR’s resistance decreases as light intensity falling on them increases.

Potentiometer uses the potential divider principle to measure potential differences and e.m.f.


The unknown potential difference OR e.m.f., VAB is applied across point A and B, with the point at higher potential connected to A.

Then J is moved along XY until a point Z where no current flows through the galvanometer (the galvanometer shows no deflection). This is the balance point where VAB is equal to VXZ. Then LXZ is known as the balance length.

$V_{AB} = V_{XZ}$

$V_{AB} = \frac{L_{XZ}}{L_{XY}} V_{XY}$

$\frac{V_{XZ}}{V_{XY}} = \frac{R_{XZ}}{R_{XY}}$

Back To DC Circuits (A Level Physics)

Back To A Level Physics Topic List

Mini Physics

As the Administrator of Mini Physics, I possess a BSc. (Hons) in Physics. I am committed to ensuring the accuracy and quality of the content on this site. If you encounter any inaccuracies or have suggestions for enhancements, I encourage you to contact us. Your support and feedback are invaluable to us. If you appreciate the resources available on this site, kindly consider recommending Mini Physics to your friends. Together, we can foster a community passionate about Physics and continuous learning.

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.