Transcript Electric current

Electric current
An introduction :
https://www.youtube.com/watch?v=1xPjES-sHwg
Electric current
Electric current is an ordered motion of charge carriers
between two points having
different electric potential ( = voltage) .
In a metal wire the charge carriers are the conduction electrons,
while in a liquid or in a gas they are ions or , or by both ions and electrons
such as in a plasma
There are two fundamental quantities in electricity:
current and voltage.
Voltage is the cause and current is its effect.
We are going to study the current in metals.
The conventional direction of the current, for historical reasons,
is defined as opposite to the direction of motion of the electrons.
http://ed.ted.com/lessons/electric-vocabulary#watch
For an electric current to flow, we need two things:
1)
something to make the
charges flow, such as a
battery , a device that is
able to maintain a
constant voltage between
two points (a potential
electric difference ), as
the water rushes down
only if there is a different
gravitational potential
energy between two
points at different
height.
For an electric current to flow, we need two things:
2) a complete path for the
current to flow in. This is
called an electric circuit.
https://www.youtube.com/watch?v=8gvJzrjwjds
How do we define the rate of current?
Current
is
the number of Coulombs
that passes
a point
during a second.
We measure it in Amps.
1C
1A 
1s
So if there is a current of 5 A flowing ,
it means that 5 C per second are
passing a given point.
q q
i 
t t
Part1 Charge and current : https://www.youtube.com/watch?v=KUMxSTgLSKM
Part 2 Charge and current : https://www.youtube.com/watch?v=MluOUYm8rZA
How do we define the voltage?
Voltage is the potential
difference between two
points : it is the potential
to do work .
It is measured in Volt.
So if there is a voltage of 5
V, it means that 1 C has
the potential to do 5 J of
work.
A revision from BBC bitesize
http://www.bbc.co.uk/bitesize/ks3/science/ener
gy_electricity_forces/electric_current_voltage
/activity/
A test from BBC Bitesize
http://www.bbc.co.uk/bitesize/quiz/q74171589