Scientific Principles PowerPoint 6 PDF

PowerPoint 6 Basic principles of electricity LESSON INTENT. Learners will look at the principles of electricity Be able to use the power an OHMs triangle # To be able to know the different between AC current & DC current All learners have to be able to describe what an anode and a c...

PowerPoint 6 Basic principles of electricity LESSON INTENT. Learners will look at the principles of electricity Be able to use the power an OHMs triangle # To be able to know the different between AC current & DC current All learners have to be able to describe what an anode and a cathode is.  PRINCIPLES OF ELECTRICITY Voltage = V The unit for electromotive force (emf). The higher the voltage the greater the force is to cause electrons to flow along the conductor (eg 240v for domestic). Current = I The ampere is the unit of current, and can be defined as the unit of quantity or volume passing down a conductor. (eg 3 amp fuse). Resistance = R The ohm is the unit of resistance, which opposes the flow of current. Watts = W It is the unit of power for an appliance. Power is used to make an appliance work; as some power is absorbed, an appliance is never 100% efficient (e.g 3kW immersion heater). Joules = J The unit of electrical energy. As this is so small, it is not generally used. Today it would be measured in the kilowatt hour, which is how electricity bills are measured. The relationship between watts – amps – volts ÷ ×  ACTIVITY 1 TRY AND WORK OUT THE FOLLOWING… 1. If an appliance needs 3kW in a domestic property, what 12.5 amp. is the fuse size? 2. In a domestic property, an appliance has a fuse size of 720wisorthe 3 amp. What 0.72kW. maximum power rating of the appliance? 3. An appliance has a 5 amp fuse and needs 1.2kW of 240v. power. What is the voltage required? Ohm’s Law shows the relationship between: voltage – current – resistance ÷ ×  ACTIVITY 2 - TRY AND WORK OUT THE FOLLOWING… 1. What would be the resistance of a domestic appliance if the fuse size was 3 amp? 80 ohms. 2. What is the fuse size for a domestic appliance which has 0.2 amp. 1,200 ohms resistance? 3. If an appliance had a fuse rated at 13 amp and the 416v. resistance was 32 ohms, what would the voltage be? AC = alternating current = mains electri (electromagnetically) The sinusoidal wave form Hz = cycles per second = 50Hz in UK DC = direct current = batteries (chemically). Dissimilar metals in a dilute acid solution Cathode eats away the anode Photovoltaic Cells  DC Symbols Rectified 12 – 24 Volts DC Battery AC Symbols AC symbol 220 – 240 Volts AC 50 Hz CHECK YOUR KNOWLEDGE OF THESE QUESTIONS. 1. What does Watts measure? 2. What is the letter that represents current? 3. What does AC mean and where is it found? 4. What does DC mean and where is it found? 5. Cathode destroys the anode true or false? TRAFFIC LIGHT IT: WHERE IS YOUR LEARNING AT? Red = I have not really understood the content we have studied today (write down 2 questions that you need help with) Amber = I have understood the content on Effective Questioning (write down 1 one question you need to clarify) Green = I have understood all the content (write down one example from what we have studied)