C8 (Charge and Current) Flashcards
Electrical charge is measured in..
Amperes (amps)
Electrical current is defined as…
The rate of flow of charge
Equation for current
I= change in Q/ change in t
One ampere is equivalent to what passing a given point per second
One coulomb of charge
What is electrical charge
A physical property
Some particles are charged like protons and electrons others like neutrons aren’t
Any object that isn’t charged is called…
Neutral
What are the two types of forces
And how do they interact
Positive and negative
Like charges repel, opposite charges attract
Electric charge is measured in…
Coulombs (C)
One coulomb is defined as….
The electric charge flowing past a point in one second when there is an electric current of on ampere
Equation for charge
Change in Q= I x change in t
Any particle that has electric charge is a…
Charged carrier
What is the value of the elementary charge
1.6 x 10^19 C
If we know the value of current in a metal wire we can calculate…
The charge passing through it in the a given time and the number of electrons (divide the charge by the charge e on each electron, the elementary charge).
The charge of most objects is usually due to a..
Loss or gain of electrons by the object
How can the size of charge on a particular object be expressed
Q=+/- ne
Q is the net charge
We describe the charge of an object as being what
And why
Quantised
This is because charge can only have certain values (that are integer multiples of e)
In a metal an electric current is usually what
A flow of electrons
Because of the way atoms are bonded, most electrons in metal atoms are fixed to their atom. However a small number of electrons from each atom are free to move.
How do electrons move
From a negative terminal to a positive one
The greater the rate of charge flow the greater…
The electric current in the wire
A larger current may be due to:
Greater number of electrons moving past a given point each second (i.e wire with large cross sectional area).
Same number of electrons moving faster through the metal
Conventional current
The flow of current from the positive terminal to a negative terminal
Electron current
The flow of electrons from the positive terminal to the negative one
Electrolytes
Liquids that can carry electric current
What is the electric current in electrolytes
Not a flow of electrons but a flow of ions