A potential divider is a simple circuit that uses resistors to supply a variable 'potential difference' (i.e. voltage).This can be used for many applications, including control of temperature in a fridge or as audio volume controls. Understanding how the resistors in the circuit allow this is important for designing many electronic circuits. Here you can investigate how changes in the two resistors can lead to different voltages across them.
Press GO to launch the experiment!
Most electrical or electronic circuits use the voltage across the circuit components to perform some task. This includes motors, sensors, speakers, computer chips, LEDs and diode lasers, communications antennas (e.g. in mobile phones), heaters, turbines, and mains electricity delivery to houses and industry.
It is important to know how to control the voltages in these circuits to make the applications work! The simplest circuit to start to understand this is the potential divider, which is made up of two resistors in series. Other circuits may be made of more advanced components but often use the same principles of how voltage (i.e. ‘potential’) division. For example: two transistors in opposite high or low resistance states and connected in series are used to define whether a ‘logic gate’ is set to a digital (‘Boolean’) value of 1 or 0, and are a fundamental building block of how a digital computer processor works.
Sensors can be made from a fixed resistor and a component that has a resistance that depends on whatever is being sensed connected, e.g. a thermistor for sensing heat or a light-dependent resistor for sensing light. A voltage applied to the two components in series allows the voltage across the fixed resistor to be a measure of the resistance of the sensing element’s resistance. This approach can avoid some difficulties of just using the single element, such as high power consumption.
Electrical heaters (including room heaters, cookers and hair dryers) use a fixed resistance heating element (e.g. a coil of wire) and a variable resistance transistor in series. The resistance of the transistor then controls how much voltage is across the heating element and, therefore, how much electrical heating is produced!
This experiment allows you to gain a good understanding of the potential divider. It also allows you to reinforce your understanding of Ohm’s law, how resistor coloured bands code for resistance, and how to use digital multimeters (DMMs), which you may have already met in the FlashyScience Ohm’s law virtual experiment.
Download the attached file to see the full Quick Guide (requires log in) or follow the instructions below:
To measure resistance:
To change a resistor:
To measure voltage and current:
Download the attached file to see the full operating instructions for the Potential Divider experiment (requires log in)
Download the attached file to see lots of Potential Divider questions and experiments (requires log in)
Download the attached file to see the Background to the Potential Divider experiment (requires log in)