Current Electricity Flashcards
What is an Electric Current?
~ Caused by the flow of electrons through a good conductor such as metal
~ A good insulator does not allow electric current to flow
Electric Charge
~ an electric current is a flow of electric charge
Conductor
~ Conductors are substances which allow electric current to flow through them freely
Insulators
~ Insulators are substances which do not allow electric current to flow through them.
Electrical Energy Can Be Converted Into…
~ Light:
Light energy so we can see in the dark
~ Heat:
Heat energy so we can cook + heat buildings
~ Kinetic:
Kinetic energy for electric motors
~ Sound:
Sound energy for music
Closed Circuits
~ A closed circuit is needed for the current to
flow
~ If there is a break in a circuit then the
current wont flow and the electrical energy
can’t get through
Batteries
• Energy provided by a battery or power
pack is needed to move the current
around the circuit
• The battery pumps electrons from its
negative end around a circuit
• The electrons travel all the way around
and are attracted back to the positive end
of the battery
• The negative end of the battery is an area
of High Electrical Pressure
• The positive end of the battery is an area
of Low Electrical Pressure
• Electrons will move from areas of High
Electrical Pressure to areas of Low
Electrical Pressure
Potential difference
• The difference in electrical pressure
between the positive and negative ends is
called the Potential Difference
• Whenever there is a potential difference
electricity will flow
• This potential difference is known as
Voltage and is measured in volts
Resistance
• Resistance is the opposition to the flow
of electrons. The unit is the Ohm (Ω),
and it is measured using an Ohmmeter
• If a Resistor is placed in an electric circuit,
it will slow down the flow of electrons
Bulbs in Series
• Like the bulb on a christmas tree, what
happens if one blows?
• The same amount of current flows through
each bulb in the series
• The voltage is split up, depending on the
size of the bulb
• If they are the same size bulbs, then the
voltage is split evenly
Bulbs in Parallel
• The lights in your house are connected in
parallel, as are car head lights
• If your bedroom light blows, is the kitchen
light affected?
• The current is split between the bulbs, if
they are the same size, then the current is
split evenly
• The same voltage flows through each bulb
Direct Current
• Direct current goes in one direction only
e.g. the current from a battery
Alternating Current
• Alternating current changes very quickly,
many times a second
• This is how the current is supplied by the
ESB
• AC can be converted to DC using a
rectifier, smoothed using a capacitor