Transcript Electric Current

Electric Current
How is water like electricity?
What is current?
Water tends to flow from high places to
low places, due to it’s potential energy
or the effect of gravity.
Electricity acts in the same manner.
Electrons will flow from a place with a
negative charge to a place with positive
charges (Opposites attract)
What is current?
Electric Current (I) is the net movement of
electrons in a single direction.
• Electric current is measured in amperes or
amps (A)
• 1 ampere = 6250 million billion electrons or
6.24 X 1018 (coulomb) flowing past a point
every second [1 A = 1 C/S]
What creates the current?
• With water, a difference in height would
make the water move.
• With electric current, you need a power
source to provide a voltage difference.
What is a voltage difference?
• The voltage difference (V) is the difference
in the voltage or the electric potential energy.
Think of it like an electric pressure.
• With a battery, electrons are on one end, the
negative end. They want to travel to the
positive end of the battery.
• Voltage is measured in volts (V)
• [ 1 volt = 1 joule/coulomb ]
What makes the light bulb glow?
Like water current, electric current can be slowed
down by bumping into things
The part of the circuit which is inside of the light bulb
is a thin wire called a filament. This filament resists
the flow of electrons; The electrons bump into the
molecules in the material and electrical energy is
converted into thermal and then radiant energy
(glow).
The filament has a high resistance.
What is resistance?
Resistance (R)- the tendency for a
material to oppose the flow of electrons.
Conductors have less resistance than
insulators. (Copper is an excellent
conductor, it has a low resistance)
Resistance is measured in Ohms (Ω)
Quiz
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What keeps the current flowing in a circuit?
The voltage difference of the battery
What makes a light bulb glow?
The resistance of the filaments in the bulb
How is water like electricity?
It has a current (I), requires a difference in
energy to keep moving (V) and can be slowed
down by objects in its path (R).
Water Analogy Animation
http://www.youtube.com/watch?v=j8Tyyg
Wl9nQ