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ALL ABOUT STATIC AND
CURRENT ELECTRICITY
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PHYSICS 1
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ELECTRIC CIRCUITSCONTENTS OF SLIDE
1. Understanding basic concept of Static electricity
2. Concept of electric charge and how moving charges results in electric current
3. Circuit Behaviour and Electric circuit 4. Understanding basic concepts in current
electricity- Electric current, Voltage and Resistance
5. Energy transfers in circuits6. Generation and Distribution of Electricity
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What is static electricity?
Students to use the next three minutes to
discuss and write down what they
already know about static electricity
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What is static Electricity?
Developing charges by rubbing• Insulators are materials that hold their
electrons very tightly as these electrons are not allowed to move. Good examples of insulators are – glass, plastic, cloth and dry hair.
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How do electrons move in insulators?
• Hint: It is important to recall that one of the reasons conductors conduct electricity is because they allow the flow/movement of electrons across it. Perhaps another reason could be because they have free electrons or electron cloud. However this is obviously not the case for INSULATORS.
• So the question again is: How do electrons move in insulators?
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How do electrons move in insulators?
One way of doing this, is to rub any two different insulators together for electrons to be transferred
from one to the other.
You should know
1. Rubbing causes friction between any two insulating materials.
2. The more the materials are rubbed, the stronger the effect and the larger the static charge that builds up.
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TWO TYPES OF CHARGESWhich of the following objects shown below
will 1. Repel2. Attract 3. Explain why they will repel or attract
Polythene Rod
Polythene Rod
A piece of cloth
Glass Rodwww.sciencetutors.zoomshare.com
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REPEL
Rubbing two identical materials and holding
them close together will repel or push each other
apart.
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ATTRACTHowever if the two rods are made of different materials, the pair
will attract.
You should Know
1. Materials will repel if they have the same type of charge.
2. They will attract if they have charges of different types.
3. The charges are not made but moved around when two object are rubbed together as a result of the friction
between them4. Rubbing does not make charge, it actually separates existing charges that
were there all along.www.sciencetutors.zoomshare.com
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ELECTRICAL CHARGES• Proton, neutrons and electrons are subatomic
particles of an atom and are very different from each other because of their electrical charge
Proton Neutron Electron Positive charge Neutral Negative charge
You should know
The charge of one proton is equal in strength to the charge of one
electron.
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How to Charge Something
Most materials have equal numbers of positive and negative charges, this
makes them electrically neutral.
1. What happens to these neutral materials when electrons are removed
or added to them?
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ELECTRIC CURRENT
Class Task (3 minutes)
1. What is electric current?
2. How is current electricity different from static electricity
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ELECTRIC CURRENT
You should know• Electric current is simply defined as the flow of electric
charge. • The flowing electric charge which moves
round a complete circuit may be either electrons or ions.
• In current electricity free electrons are responsible for the passage of current
in a complete circuit
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SIMPLE CIRCUITS
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For • Simple circuits and concepts• Circuits calculations• Quiz questions on circuits• Class Task/Activities on electrical
circuits and static electricity
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ELECTRICAL POWER
What is electrical power?
Electric power is defined as the rate at which electrical energy is
transferred from the stored source example a battery to
other components by an electric circuit.
Unit of Power is the watt (W)Power = Current × Voltage
P = I × V
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Understanding Power Equations
Power = Current × VoltageP = I × V
Current = Power ÷ Voltage
Voltage = Power ÷ Current
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POWER CALCULATIONS
An electric kettle connected to the 240 V mains supply in a kitchen draws a current of 15 A. Calculate
1. The power of the kettle2. The energy transferred in 1 minute
NOTE – ensure you write down formula first.
To calculate energy transferred in 1 minute you need to use the equation shown below . Remember time has to be in seconds.
Power = Current × VoltageP = I × V
Energy transferred (E) = power (P) × time (t)(t)
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Our Electrical Appliances at Home
Knowing the cost of electricity your appliances are using is very important.
Kilowatt-hour is a unit of energy. This is calculated as
Class Task
What is the cost at 10p per kWh for a 2500 W electric radiator is used for 12 hours ?
Energy transferred = power × time (in kWh) (in kW) (in hours)
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Our Electrical Appliances at Home
Class Task (6 minutes)1. A 3kWh fire, a 240W TV and three 120
W lamps are all switched on from 5p.m to 11p.m. What is the cost at 10p per kWh?
2. Nikki bought a new vacuum cleaner labelled 250 V 600 W. How much current does it take when connected to a 250 V supply
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Hints for Calculation1. A 3kWh fire, a 240W TV and three 120 W
lamps are all switched on from 5p.m to 11p.m. What is the cost at 10p per kWh?
If 1kW = 1000W what is 240 W and 120W? common sense calculation
1 hour = 3600 seconds again common sense how many hours are there between 5p.m and 11p.m
• Well done work it out.
Energy transferred = power × time (in kWh) (in kW) (in hours)
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Distributing Electricity
Class Task (Discuss with the person next to you and write down
answers to the following)
1. What is a TRANSFORMER
2. Write down or draw any two types of transformer you know or have studied
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TRANSFORMERSA transformer is simply an electrical device that either raises or lowers the voltage of electricity in distribution.
You should know
The behaviour of a transformer depends on the number of turns of wire on the primary
or secondary coils of the transformer.
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Transformer - Induced Voltage
Induced voltage – this is the voltage generated or induced in the secondary coil of a transformer by the changing
current in the primary coil
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Transformer – Applied Voltage
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for
• Transformer concepts• Transformer calculations• Quiz questions• Class Task/Activities on electrical
circuits and static electricity
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STEP UP AND STEP DOWN
• You will need to understand the following concept before looking at how to step up or step down a transformer.
