Contents
Key Stage 3
Meaning
Resistance is a description of how difficult it is to increase the current through a conductor when increasing the potential difference.
About Resistance
- The unit of resistance is the Ohm (Ω).
- Resistance cannot be directly measured. Resistance must be calculated by dividing the Potential Difference by the Current.
- Conductors have a low resistance and insulators have a high resistance.
Equation
\[Resistance = \frac{Potential Difference}{Current}\] \[R = \frac{V}{I}\] Where:
- R = Resistance
- V = Potential Difference
- I = Current
Example Calculations
A student measures a potential difference of 5V across a component and a current of 0.1A. Calculate the resistance. | A bulb has a current of 200mA passing through it and a potential difference of 12V across it. Calculate the resistance of the bulb. | Calculate the resistance of a buzzer connected in series to a 6V battery with an ammeter reading of 10mA. |
Potential Difference = 5V Current = 0.1A \(R = \tfrac{V}{I}\) \(R = \tfrac{5}{0.1}\) \( R = 50 \Omega\) |
Potential Difference = 12V \(R = \tfrac{V}{I}\) \(R = \tfrac{12}{0.2}\) \( R = 60 \Omega\) |
Potential Difference = 6V \(R = \tfrac{V}{I}\) \(R = \tfrac{6}{0.01}\) \( R = 600 \Omega\) |