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Electricity
Electricity
•Static •Current
Electricity occurs in 2 different forms
Current Electricity
• Moving electricity• Electrons flow through a conductor - material that allows electrons to flow through
• Circuit = continuous loop for electrons to flow
• Needs energy supply
Electrical components
•Wire•Ammeter•Battery•Fuse•Connected wires
•Bulb•Switch•Voltmeter•diode•Resistor•Rheostat
CIRCUIT TYPESThe simplest type of circuit involves electricity going around with no “choices” (electrons don’t really choose).This is called a Series circuit.
Draw the path the electrons travel-out the negative toward the positive
The other main type of circuit has two or more branches.
This is called a Parallel circuit.
Draw on the electron flow.
What sort of circuit is this?
A parallel… but, more importantly…
A short circuit.
Series circuit
• Has a single loop for electrons to travel round
• Components are connected one after another
• Current has to travel through all components
• Current is the same at all points• Voltage is shared between components
• It is either all on or all off
Series circuit
• http://www.ndt-ed.org/EducationResources/HighSchool/Electricity/seriescircuit.htm
Parallel circuit
• Has two or more paths for electrons to flow down
• Current is shared between the branches
• Sum of the current in each branch = total current
• Voltage loss is the same across all components
Practice
• http://lgfl.skoool.co.uk/keystage3.aspx?id=93
Current (I)
Current is the flow of electronsaround a circuit• DC = direct current like battery
• Electrons flow in one direction• AC = Alternating current like mains
• Electron flow changes direction 50x per second
Ammeter
• Measures CURRENT(I)• Unit = Amp (A)• Current is flow of electrons• Connect in series at the point you wish to measure
Voltage (V)
Gain or loss of energy as itpasses through a component• Voltage lost = voltage gained• In series voltage loss is shared between components
• In parallel voltage loss is the same across all components
Voltmeter
• Measures voltage• Unit = Volt (V)• Voltage increases as it passes through energy suppliers
• Voltage is decreased as it passes through users
• Connect in parallel around a component
SUMMARY
In Series In Parallel
Current
Voltage
Always the same The branches share electrons and add to the total
Voltage from source = voltage used
Voltage is shared between power users
Voltage is the same in all branches
Resistance (R)
The amount that a component slows the current
•As the electrons are slowed by a resistor, energy is lost in the form of heat.
•This means that current, resistance and voltage must be linked.
•This is Ohms law
•The unit of resistance is the ohm, symbol V
I R×
Power
Energy used by component per second
• Unit of power is the Watt, symbol is W• One watt means that 1 joule of electrical energy is being used up per second.
• Current, voltage and power are linked P
I V×
Electricity Generation
• Brainstorm ways to generate electricity
Fossil Fuels
Hydro Dam
Hydroelectric power
Nuclear power
Wind Power
Tidal Power
Geothermal
Solar
• Solar water heating• Photovoltaic cells• Solar furnace
PROBLEMS
1. Fill in the gaps in the table.
a b
c d
e f
g h
i j
k l