7.5 I-V graphs Flashcards
What do I-V graphs show
Show how current varies as you change the potential difference (V) across a component
How is resistance found from a I-V graph?
It is the gradient (plot V on the x-axis and I on the y-axis)
HOw is the resistance different in linear adn non-linear components?
Linear components have straight line I-V graphs (resistance remains constant as the current is changed)
Non-linear components have curved I-V graphs - resistance changes depending on the current
Draw a set-up to investigate the I-V graph of a component
How do you conduct an experiment to investigate the I-V graph of a component?
Change the resistance in the variable resistor (to alter the current). For each setting, measure and plot the current and potential difference across the component. (Take three readings for each current and take an average)
Swap the wires over connected to the battery to reverse the direction of the current, and repeat as above.
What does an I-V graph for a fixed resistor look like?
Current is directly proportional to the potential difference -so yo uget a striaght line IV graph (assuming temperaure is constant)
hat does an I-V gaph for a filament lamp look like?
Curved IV graph (S-shaped).
The filament heats up and glows with electric current. Resistance increases with remperature, so as more current flows through the lamp, the lamp heats up and resistance increases, so less current can flow per unit potential difference (making the graph shallower)
What is a diode?
A component that only allows current pass through it in one direction
What does an IV graph for a diode look like?
What does an IV graph for a thermisor look like
S-shaped curve, but it gets steeper as the current increases (as the temp goes up, making the resistance lower)
What does an IV graph for an LDR look like?
Straight line.
Assuming light level is constant, the LDR will behave like a fixed resistor.
