3.1 Capacitors Flashcards
What is a capacitor?
A device that stores charge
What is capacitance?
Charge stored per unit voltage
What does a capacitor consist of?
Two conducting layers spectated by an insulator
Why is work done to charge a capacitor?
To overcome the repulsion of electrons approaching the negatively charged plate
What is the voltage across a capacitor when it is fully charged?
All of the supply voltage
What does the graph of current against time look like for s charging capacitor?
Negative sloping curve
Y intercept is initial current
O current when capacitor is fully charged
What does the graph of voltage against time look like for a changing capacitor?
Positive sloping curve
Voltage across the capacitor
Reaches a horizontal line at the supply voltage when the capacitor is fully charged
What does the graph of current against time look like for a discharging capacitor?
Positive sloping curve but negative (negative initial current)
What does the graph of current against time look like for a discharging capacitor?
A negative sloping curve
What happens if a capacitor is replaced with a larger one?
It increases charge time and increases energy stored
What happens if a larger resistance is put in the circuit?
It increases charge time and decreases initial current
