Core Practical: Investigating & Testing Circuits Flashcards
All 4 cards in this deck
What are the steps of the core practical to obtain current–potential difference data for a filament lamp?
e.g. a filament lamp on a low-voltage supply
- Connect the lamp in series with the supply, an ammeter and a variable resistor, with a voltmeter in parallel across the lamp.
- Adjust the variable resistor and record the current and p.d. at each setting.
- Plot a graph of current against potential difference.
How is a voltmeter connected to measure the potential difference across a resistor?
In parallel, across the resistor.
How is an ammeter connected to measure the current through a component?
In series with the component.
Why should the circuit be switched off between readings when finding the I–V graph of a fixed resistor?
To stop the resistor heating up, since a temperature rise would increase its resistance.