2. Electricity (required practical 3 - resistance) Flashcards
What is the practical?
investigating the factors affecting the resistance of electrical circuits
What are the steps for the required practical (factors affecting resistance)?
- First set up a series circuit and thin wire taped across a metre ruler
- Attach the crocodile clips onto the wire at 0 cm then increase the length of the wire by the same amount for each reading, by moving the crocodile clips further away from each other
- Each time record the current and potential difference
- Rearrange and use the formula V= IR to measure the resistance
- Plot these values in a graph
What is the resistance of the wire directly proportional to?
the length of the wire
What should the resistance go straight through in the graph of the required practical?
Through the origin, if it doesn’t then there may have been a systematic error
What does the graph look like for the resistance required practical?
How does the length of wire affect resistance?
As the length of wire increases, resistance also increases
How does the diameter of wire affect resistance?
As the diameter increases, the flow of current increases, so the resistance decreases
Why is there a small resistance when the length of the wire is zero?
it should not be there, so is a problem with the method (zero error)
What is an issue with the experiment?
if the temperature of the wire increases, then the resistance will also increase
How can we reduce the chance of the temperature of the wire increasing?
only turn on the current when taking a reading
What happens as temperature increases?
resistance increases
What happens as the length of wire increases?
resistance increases
What happens as the diameter of wire increases?
the flow of current increases, so the resistance decreases
