# Design and Use of Circuits to Explore the Variation of Resistance

## Design and Use of Circuits to Explore the Variation of Resistance

• Understand the meaning of resistance in an electrical circuit: it’s a measure of how difficult it is for an electrical current to pass through a component in the circuit. It is measured in ohms (Ω).
• Note that Ohm’s Law states that the current (I) in a circuit is directly proportional to voltage (V) and inversely proportional to resistance (R). This can be written as I = V/R. Thus, you can increase the current by increasing the voltage or decreasing the resistance.
• Appreciate that resistance varies with different factors. This includes the material of the component (e.g. conductive materials have low resistance), the thickness of the component (the thicker the component, the lower the resistance), and the temperature (as temperature increases, so does resistance).
• Recognise that when you are designing circuits to explore the variation of resistance, you should include a method to measure both current and potential difference, usually an ammeter and voltmeter.
• Appreciate that when designing a circuit to investigate resistance, a variable resistor can be included to alter the resistance, and thus the current flowing through the circuit. This will demonstrate how resistance affects the current flow.
• Understand that the resistance of a component can be found by creating a circuit with the component, a battery, an ammeter and a voltmeter. Measure the current through and voltage across the component, then apply Ohm’s Law.
• Note that when experimenting with resistance, one could use a rheostat or a potentiometer, which allows you to change the resistance in a circuit smoothly and continuously.
• Remember safety measures while handling electrical circuits, especially when working with high voltages or currents. Always switch off the power supply before making any changes to the circuit. Also, ensure wires and components are in good condition before using them.
• Understand how to draw simple circuit diagrams using standard symbols for common components. This is an important skill in both designing and documenting your exploration of resistance.