J.C Physics

1. J.C Physics

2. Created by the class of…. • 3Br & 3Da • CBS Kilkenny 2012

3. Use simple materials to generate static electricty STATIC ELECTRICTY

4. Method • 1.Rub a plastic biro against the sleeve of your jumper • 2.The biro will pick up small pieces of paper

5. Conclusion • This happens because the pen becomes negatively charged. 

6. Conversion of Electrical Energy to Magnetic to Kinetic Energy

7. Method

8. Method • Connect 6 V battery to nail • Wrap wire around nail • Turn on battery • Put nail near paper clips

9. Results • The nail was magnetised. It picked up the paper clips

10. To test electrical conduction in a variety of materials Perspex rod wire A conductor is a material through which an electrical charge can flow.An insulator is a material through which an electrical charge cannot flow.

11. To see if a piece of wire conducts electricity An additional wire is inserted here Result – the light bulb will light up showing that wire is a conductor of electricity Set up the circuit. Connect the wire to the circuit as shown on in the diagram.

12. To see if a Perspex rod conducts electricity Insert a Perspex rod here instead of the wire Result – the light bulb will not light up showing that the Perspex rod is not a conductor of electricity Set up the circuit as before. Replace the wire with a Perspex rod.

13. To Plot the Magnetic Field of a Bar Magnetic Equipment;1 Barmagnet,2 Science books ,a Sheet ofplain paper, iron filings . Step 1;Wedge the Bar magnet between the the two books. Step 2;Place the sheet of paper overthe two books .

14. Step 3 ;Sprinkle the iron filings over the sheet and watch for result • Result ; A picture of the magnetic poles should be visibly clear • POD

15. Amps measured with Ammeter Connect the Battery and the Ammeter together Attach a lamp onto the circuit Observe

16. Measuring Voltage with a voltage meter • 1.Connect the voltage meter , battery and bulb into a circuit • 2. Observe the results on the voltage meter

17. Resistance • Measured using an ohmmeter. • Units= ohms

19. Alternating current (A.C) • A current that is continually changing in direction

20. Domestic Voltage supply • 240 volts

21. What happens a LDRs resistance measure under varying degrees of light brightness

22. 1.If bright light falls on a LDR the resistance is low . A larger current can flow through the resistor . • 2.If dim light falls on a LDR the resistance is high . A smaller current will now flow through the resistor .

23. 3.Using a LDR you can arrange for an electrical appliance to be controlled by light . In fact,some appliances can be switched on or switched or switched off by simply shining light on the LDR connected to them .

24. Unit of electrical energy = kilo watt-hour {kWh}Name 3 wires in a plug = earth/live/neutral

25. WORK,POWER AND ENERGY Work= force x distance Force= Newtons (N) Distance= Metres (m) Work=joules (J)

26. Sources of energy Advantages + Disadvantages

27. Non-renewable sources of energy Non-renewable sources of energy are sources that will eventually run out another name for them is fossil fuels e.g. Oil + gas etc. Advantages; • Easy to get. • Reasonably cheap. Disadvantages; • Causing greenhouse gas emissions. • Polluting the atmosphere e.g. Acid Rain.

28. Renewable sources of energy Because fossil fuels are finite , we try to improve our efficiency of the renewable sources of energy. Examples; • Solar Energy • Hydro Electricity • Wind Energy • Nuclear Energy

29. Solar Energy Solar energy is taken straight from the rays of the sun. We convert solar energy to electrical energy using Solar Cells. We also convert energy to heat energy using solar panels. Advantages; • Solar energy is free. • Solar energy does not cause pollution. Disadvantages; • The efficiency of solar cells needs to be improved as only a small percentage of energy is converted to electrical energy. • Solar cells are expensive to make.

30. Hydro-Electricity By building a dam in a large river it is possible to build a vast amount of water. This water has potential energy when stored behind the dam wall. When the water is released it becomes kinetic, this kinetic energy is changed into electrical energy Advantages; • Does not cause pollution. • cost efficient way to produce energy. Disadvantages; • Flooding can destroy plant + animal habitats. • Building dams can cause flooding in valleys inhabited by people.

31. Wind Energy On a windy day, the moving air has a large amount of kinetic energy. The idea is to change this kinetic energy to electrical energy. Advantages; • Does not cause pollution. • Wind energy is free. Disadvantages; • No electricity produced on a clam day. • Large propeller masts are noisy and spoil the natural beauty of the countryside.

32. Nuclear Energy Nuclear energy is usually considered as renewable energy. One form, nuclear fission, uses materials like Uranium. Uranium is finite. However another fusion is used with the basic material , water. However the technology for generating electricity from nuclear power is not yet available. Advantages; • Nuclear fusion would use a fuel in plentiful supply. • Nuclear energy would reduce the greenhouse emissions. Disadvantages; • Danger of a nuclear explosion. • Harmful effects of radioactive waste.

33. Other Types of Energy Tidal and Wave Energy; The kinetic energy of the waves and the tide is converted to electrical energy. Geothermal Energy; Heat energy can be trapped beneath the surface of the Earth. This heat can also be used to heat homes or converted to electrical energy. Biomass Energy; Some plants grow very quickly e.g. Sugar Cane. The oil from the plants is converted to alcohol and in cars instead of petrol.

34. Converting Light energy to Electrical energy to Kinetic energy By Declan Wall

35. Connect the solar cells to the solar motor • Shine light from the lamp onto the solar cells • See page 320 in text book

36. Conclusion • The light energy from the lamp was converted to electrical in the solar cells which was converted to kinetic energy in the moving fan

37. APPLICATIONS OF LEVERS Levers are designed to lift objects with less effort than you would have on your own. Modern day uses for levers are in some cranes and heavy machinery.

38. EFFORT The effort is where the lever gets its input. For example, on a tweezers, the part you push down on is the effort.

39. LOAD The load is the item being moved by the lever. For example, a tractors loader lifting a bale, the bale is the load.

40. FULCRUM The fulcrum is the point where the lever pivots. For example, the wheel on a wheelbarrow is the fulcrum.

41. Why do objects float on water?Objects float on water because the object is less dense than the liquid.What is meant by force?Force causes a stationary objectto move.What is the unit of force?The unit of force is newton and the symbol is N.

42. PRESSURE

43. What is Pressure • Pressure is force per unit area • Pressure = Force divided by Area • The pressure due to a force depends on two things • Pressure increases when the force increase • Pressure increases when the area that the force is acting on decreases • Pressure is measured in newtons per metre squared.

44. Pressure Mathematical Example A stone block of weight 225000N is to be used as a base for a sculpture. The block has dimensions 3m x 2m x 1.5m. (i) What is the greatest possible pressure that the block could exert on the ground (ii) What is the least possible pressure that the block could exert on the ground

45. Pressure in Liquids • Why do divers need to wear protective suits when diving? • It is because the weight of the water above them exerts a great pressure. The diving suits stops the diver being squashed. • If a diver comes up too quickly the change in pressure can be very dangerous. Bubbles of nitrogen form in the blood. This is a condition known as the bends

46. Atmospheric Pressure • Air is made up of particles of various gases. These are attracted to the earth by gravity thus they have a weight. • The pressure due to the weight of air pressing down on the earth is called atmospheric pressure. • This pressure acts on our bodies but luckily the pressure inside our body exerts an equal pressure outwards to balance this.

47. Atmospheric Pressure • As we increase our height above sea level the atmospheric pressure decreases. • Our ears ‘popping’ is our body’s way of equalising the pressure on either side of our ear drum. • In space there is no atmospheric pressure so the pressure from inside our body would have no outside pressure to balance in. This means astronauts might explode without special suits!!

48. Measuring Pressure • A barometer is an instrument used to measure atmospheric pressure. • There are two types of barometer: • Mercury • Aneroid Normal atmospheric pressure is written as 76cm of mercury

49. Atmospheric Pressure and Weather • The atmosphere is like a blanket around the earth. It is like a ‘sun block’ for the earth. • Atmospheric pressure changes with the weather. • Isobars joins places of equal pressure. If the isobars are close together winds will be strong. If far apart winds will be light

50. Atmospheric Pressure and Weather • If the pressure over a particular area is high it will mean fine weather. • Low pressure areas will generally be windy and wet.