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<ul><li> 1. ALL ABOUT STATIC AND CURRENT ELECTRICITY 06/06/09 07:49 PM www.sciencetutors.zoomshare.comPHYSICS 1</li></ul> <p> 2. ELECTRIC CIRCUITS </p> <ul><li>CONTENTS OF SLIDE </li></ul> <ul><li>Understanding basic concept of Static electricity </li></ul> <ul><li>Concept of electric charge and how moving charges results in electric current </li></ul> <ul><li>Circuit Behaviour and Electric circuit</li></ul> <ul><li>Understanding basic concepts in current electricity- Electric current, Voltage and Resistance </li></ul> <ul><li>Energy transfers in circuits </li></ul> <ul><li>Generation and Distribution of Electricity </li></ul> <ul><li> </li></ul> <p>06/06/09 07:49 PM 3. What is static electricity? </p> <ul><li>Students to use the next three minutes to discuss and write down what they already know about static electricity </li></ul> <p>06/06/09 07:49 PM 4. What is static Electricity? </p> <ul><li>Developing charges by rubbing </li></ul> <ul><li>Insulatorsare materials thathold their electrons very tightlyas these electrons are not allowed to move. Good examples ofinsulatorsare glass, plastic, cloth and dry hair. </li></ul> <p>06/06/09 07:49 PM 5. How do electrons move in insulators? </p> <ul><li>Hint: It is important to recall that one of thereasons conductors conduct electricity is becausethey allow the flow/movement of electrons across it.Perhaps another reason could be becausethey have free electrons or electron cloud.However this is obviously not the case for INSULATORS. </li></ul> <ul><li>So the question again is:How do electrons move in insulators? </li></ul> <p>06/06/09 07:49 PM 6. How do electrons move in insulators? </p> <ul><li>One way of doing this, is to rub any two different insulators together for electrons to be transferred from one to the other. </li></ul> <ul><li>You should know </li></ul> <ul><li>Rubbing causes friction between any two insulating materials. </li></ul> <ul><li>The more the materials are rubbed, the stronger the effect and the larger the static charge that builds up. </li></ul> <p>06/06/09 07:49 PM 7. TWO TYPES OF CHARGES </p> <ul><li>Which of the following objects shown below will</li></ul> <ul><li>Repel </li></ul> <ul><li>Attract</li></ul> <ul><li>Explain why they will repel or attract </li></ul> <p>06/06/09 07:49 PM Polythene Rod Polythene Rod A piece of cloth Glass Rod 8. REPEL </p> <ul><li>Rubbing two identical materials and holding them close together will repel or push each other apart. </li></ul> <p>06/06/09 07:49 PM + + For more science resources 9. ATTRACT </p> <ul><li>However if the two rods are made of different materials, the pair will attract. </li></ul> <ul><li>You should Know </li></ul> <ul><li>Materials will repel if they have the same type of charge. </li></ul> <ul><li>They will attract if they have charges of different types. </li></ul> <ul><li>The charges are not made but moved around when two object are rubbed together as a result of the friction between them </li></ul> <ul><li>Rubbing does not make charge, it actually separates existing charges that were there all along. </li></ul> <p>06/06/09 07:49 PM 10. ELECTRICAL CHARGES </p> <ul><li>Proton ,neutrons andelectrons are subatomic particles of an atom and are very different from each other because of their electrical charge </li></ul> <ul><li>ProtonNeutronElectron </li></ul> <ul><li>Positive chargeNeutralNegative charge </li></ul> <ul><li>You should know </li></ul> <ul><li>The charge of one proton is equal in strength to the charge of one electron.</li></ul> <p>06/06/09 07:49 PM + - 11. How to Charge Something </p> <ul><li>Most materials haveequal numbersofpositive and negative charges , this makes themelectrically neutral. </li></ul> <ul><li>What happens to these neutral materials when electrons are removed or added to them? </li></ul> <p>06/06/09 07:49 PM Visit : 12. ELECTRIC CURRENT </p> <ul><li>Class Task (3 minutes) </li></ul> <ul><li>What is electric current?</li></ul> <ul><li>How is current electricity different from static electricity </li></ul> <p>06/06/09 07:49 PM 13. ELECTRIC CURRENT </p> <ul><li>You should know </li></ul> <ul><li>Electric currentis simply defined as the flow ofelectriccharge.</li></ul> <ul><li>The flowing electric charge which moves round a complete circuit may be either electrons or ions. </li></ul> <ul><li>In current electricity free electrons are responsible for the passage of current in a complete circuit </li></ul> <p>06/06/09 07:49 PM 14. SIMPLE CIRCUITS </p> <ul><li>Go </li></ul> <ul><li>For</li></ul> <ul><li>Simple circuits and concepts </li></ul> <ul><li>Circuits calculations </li></ul> <ul><li>Quiz questions on circuits </li></ul> <ul><li>Class Task/Activities on electrical circuits and static electricity </li></ul> <p>06/06/09 07:49 PM 15. ELECTRICAL POWER </p> <ul><li>What is electrical power? </li></ul> <ul><li>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.</li></ul> <ul><li>Unit of Power is the watt (W) </li></ul> <p>06/06/09 07:49 PM Power=CurrentVoltage P=IV 16. Understanding Power Equations 06/06/09 07:49 PM Power=CurrentVoltage P=IV Current=PowerVoltage Voltage=PowerCurrent 17. POWER CALCULATIONS 06/06/09 07:49 PM </p> <ul><li>An electric kettle connected to the 240 V mains supply in a kitchen draws a current of 15 A. Calculate</li></ul> <ul><li>The power of the kettle </li></ul> <ul><li>The energy transferred in 1 minute </li></ul> <ul><li>NOTE ensure you write down formula first. </li></ul> <ul><li>To calculate energy transferred in 1 minute you need to use the equation shown below . Remember time has to be in seconds.</li></ul> <p>Power=CurrentVoltage P=IV Energy transferred(E)= power(P)time (t) (t) 18. Our Electrical Appliances at Home </p> <ul><li>Knowing the cost of electricity your appliances are using is very important. </li></ul> <ul><li>Kilowatt-hour is a unit of energy. This is calculated as</li></ul> <ul><li>Class Task </li></ul> <ul><li>What is the cost at 10p per kWh for a 2500 W electric radiator is used for 12 hours ? </li></ul> <p>06/06/09 07:49 PM Energy transferred=powertime (in kWh)(in kW)(in hours) 19. Our Electrical Appliances at Home </p> <ul><li>Class Task (6 minutes) </li></ul> <ul><li>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?</li></ul> <ul><li>Nikki bought a new vacuum cleaner labelled 250 V 600 W. How much current does it take when connected to a 250 V supply</li></ul> <p>06/06/09 07:49 PM 20. Hints for Calculation </p> <ul><li>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?</li></ul> <ul><li>If 1kW = 1000Wwhat is 240 W and 120W? common sense calculation </li></ul> <ul><li>1 hour = 3600 seconds again common sense how many hours are there between 5p.m and 11p.m </li></ul> <ul><li>Well done work it out. </li></ul> <p>06/06/09 07:49 PM Energy transferred=powertime (in kWh)(in kW)(in hours) 21. Distributing Electricity </p> <ul><li>Class Task</li></ul> <ul><li>(Discuss with the person next to you and write down answers to the following) </li></ul> <ul><li>What is a TRANSFORMER </li></ul> <ul><li>Write down or draw any two types of transformer you know or have studied </li></ul> <p>06/06/09 07:49 PM 22. TRANSFORMERS </p> <ul><li>A transformer is simply an electrical device that either raises or lowers the voltage of electricity in distribution. </li></ul> <ul><li>You should know </li></ul> <ul><li>The behaviour of a transformer depends on the number of turns of wire on the primary or secondary coils of the transformer. </li></ul> <p>06/06/09 07:49 PM 23. Transformer - Induced Voltage </p> <ul><li>Induced voltage this is the voltage generated or induced in the secondary coil of a transformer by the changing current in the primary coil </li></ul> <p>06/06/09 07:49 PM 24. Transformer Applied Voltage </p> <ul><li>Go </li></ul> <ul><li>for </li></ul> <ul><li>Transformer concepts </li></ul> <ul><li>Transformer calculations </li></ul> <ul><li>Quiz questions </li></ul> <ul><li>Class Task/Activities on electrical circuits and static electricity </li></ul> <p>06/06/09 07:49 PM 25. STEP UP AND STEP DOWN </p> <ul><li>You will need to understand the following concept before looking at how to step up or step down a transformer. </li></ul> <p>06/06/09 07:49 PM </p>


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