Unit 4.1 - Capacitance Flashcards
Capacitor
Any two conductors that are separated by an insulator
What happens when a capacitor is connected to a battery?
A small current flows for an instant as the emf of the battery “pumps” electrons around the circuit
What do the electrons do when a capacitor is connected to a battery?
The flow of electrons collect on the negative plate and leave the other plate positive
What is the total charge on a capacitor and why?
Zero
The capacitor carries an equal but opposite charge
Where are electrons drawn to and where are electrons repelled from?
Drawn to: the end to the positive terminal
Repelled by:the emf from the negative terminal
What is the total charge on a capacitor and why?
Since the total negative charge on one end is equal to the positive charge on the other end
What is the potential difference equal to when the capacitor is only just connected to the battery?
Equal to the battery charge
What do we say capacitors have on them when we discuss them?
Charge Q
Charge on a capacitor at a higher potential
Charge +Q
Charge of a capacitor at a lower potential
Charge -Q
What do we mean when we talk about the charge on a capacitor?
The separated charge
Describe the charge is if 1C of charge has been pulled from positive to negative on a capacitor?
The total charge isn’t 2C, it’s just 1C that’s been separated
What could a capacitor be considered to be?
A deceive for storing charge
How could the capacitance of a capacitor be considered metaphorically?
Capacitor - a bucket storing water
Capacitance - the volume of the bucket
Capacitance
The ability of a component or circuit to collect and store energy in the form of electrical charge
How can a capacitor be constructed simply?
From two metal plates separated by air
What is needed to pump electrons from the positive plate to the negative plate in a capacitor and why?
A large emf
It isn’t easy to remove a charge from one plate to another
What do electrical charges do to each other and what is this according to?
According to electrostatic theory, electrical charges either attract or repel each other
What does the work done when something is charged depend on?
1.) whether the charges attract or repel
2.) the size of the charge
3.) the electrical properties and dimensions of the charged object
What is used as a measure of the energy required for work to be done when something is charged?
The electrical potential
Electrical potential
An object has a potential of 1V if 1J of work is done to bring 1 coulomb of positive charge from infinity to that object
Work done is the electrical potential is positive
More than 0
Work done if the electrical potential is negative
Less than zero
What is the effect of putting charge Q on an insulated object?
Raises its potential to V