Energy and Energy Conversions - General Physics - Solved Exam, Exams of Physics

Download Energy and Energy Conversions - General Physics - Solved Exam and more Exams Physics in PDF only on Docsity! 1 Exam questions Renewable and non-renewable energy 1. [2011] Give two examples showing that the sun is our primary source of energy. 2. [2001 OL][2008 OL][2012 OL] Pick two forms of renewable energy from the list on the right. 3. [2009 OL] Pick two forms of non-renewable energy from the list on the right. 4. [2007 OL][2007] Nuclear energy could be used to solve Ireland’s energy shortage. Give one advantage and one disadvantage of using nuclear energy to generate electricity. 5. [2008] Some equipment can convert the energy of waves in seas into electrical energy. Give one advantage and one disadvantage of generating electrical power in this way. 6. [2009] Give one advantage or one disadvantage of fitting solar panels to your home. 7. [2006] Suggest two alternative sources of energy (instead of fossil fuels) for the generation of electricity in Ireland. 8. [2008] (i) Name the energy from the sun that the solar panel changes into electricity. (ii) The electrical energy is then changed into a form of energy that can be stored in a battery Name the form of energy that can be stored in a battery. (iii)In winter it may be dark when the pupils are going to or coming from school. Give two energy conversions that occur to produce the flashes of light warning motorists approaching the school on dark mornings. 9. [2010] Light, from the sun is a renewable source of energy. Ireland only uses about 2% renewable sources to meet current energy needs. (i) Name two renewable energy sources, excluding sunlight, that are available in Ireland. (ii) Give two benefits that Ireland would get from increasing the use of renewable energy sources to meet our energy requirements. 10. [2011] Compact fluorescent lamps (CFLs), shown in the photograph, have a Grade A rating (efficiency rating).Electrical energy is converted into light and one other form of energy in bulbs. (i) Name this second form of energy. (ii) Which form of energy does the more efficient bulb produce more of? (iii)Name another electrical appliance where checking the energy efficiency rating would be important to save money on running costs. Coal Oil Solar Tidal 2 11. [2012] Renewable energies are shown in the picture. (i) Pick any two of the energies shown in the picture and name your selection. (ii) Give one advantage associated with each energy you’ve selected. Two different reasons must be given. (iii)Give one disadvantage associated with each energy you’ve selected. Two different reasons must be given. Energy Conversions 12. [2006 OL] Energy cannot be created or destroyed but it can be changed from one form to another e.g. chemical energy can be converted into heat energy. Describe an experiment you could carry out to show the conversion of chemical energy to heat energy. Draw a labelled diagram of any equipment used. 13. [2008 OL] The diagram shows a common light bulb. List the two main energy changes that take place when the bulb is in use. 14. [2011 OL][2010 OL] When each of these appliances is used energy conversions take place. Copy the table into your copy and correctly match an appliance with an energy conversion that takes place when it is used. [Note: An appliance may be used more than once.] 15. [2006 OL] Give an example from everyday life where electrical energy is converted to kinetic energy. 16. [2009] Give two useful energy conversions that occur when a drill is being used. 17. [2008] Fill in the missing words in both sentences. (i) The stretched rubber chord has ______________ energy. (ii) If the stone is released it will have ____________ energy. 18. [2007] When work is done energy is converted from one form to another. Identify one energy conversion that occurred when a car brakes. 19. [2012] The conversions of chemical energy to kinetic energy to potential energy occurs when you walk up a stairs. Give two more everyday examples of energy conversions and the contexts in which they occur. Electrical to heat Electrical to sound Chemical to electrical Chemical to heat Heat to light Potential to kinetic 5 1. Syllabus: Classify sources of energy as renewable or non-renewable This is relatively straightforward, although it could be argued that power from the sun will eventually ‘run out’, but I think for the purposes of this syllabus we can consider that it’s not going to run out before we do. Nuclear energy is a little trickier. Technically the fuel for nuclear fission is non-renewable, while fuel for nuclear fusion can be considered to be renewable. For exam purposes I think we can assume nuclear energy to be renewable. 2. Syllabus: State the principle of conservation of energy While this may seem straightforward, and can indeed be ‘learned off’, it would mean passing over the opportunity to discuss one of the foundation stones of science itself. What this means is that at the moment of ‘the Big Bang’ a certain amount of energy was created and this amount has not increased or decreased one iota in the last 13.6 billion years between then and now. Now the textbooks don’t mention this (at Junior Cert or Leaving Cert) but we really have no idea why this is, but depending on your point of view this can be simply incredulous, unbelievably confusing or unbelievably wonderful (or, I suppose, all three). So every time you lift your hand you are using energy which originated 13.6 billion years ago. It’s also interesting to note that due to the the Conservation of Energy, you can’t actually ‘waste’ energy; it just gets converted into less useful forms, and usually ends up heating the air around us by a tiny amount. 3. Syllabus: Explain why the sun is considered our primary source of energy and how this is important in food production and energy supply Most of our energy can be traced to the sun (the sun provides heat and light which allow food to grow, some of which gets eaten directly, more decays to peat, coal, oil, etc). 4. Syllabus: List the advantages and disadvantages of different energy sources, including nuclear sources of energy, as part of the solution to national energy needs This is a wonderful opportunity to introduce global warming, but for reasons outside my ‘kin the concept itself does not need to be understood. It would be nice to blame others for this, but I suspect a large portion of responsibility lies with us as professional teachers; if we can’t be bothered to make any noise about it, why should anyone else? 5. Syllabus: Identify different forms of energy and carry out simple experiments to show the following energy conversions: a. chemical energy to electrical energy to heat energy b. electrical energy to magnetic energy to kinetic energy c. light energy to electrical energy to kinetic energy The best approach is to put all the resources out on the benches and let the students move between them, taking down diagrams and noting the energy conversions involved with each demonstration, along with answering any relevant questions from the work-book. 5.1 chemical to electrical to heat There is a tray of calorimeters available in the Resource Room. 5.2 electrical to magnetic to kinetic • There is a tray of electromagnets available in the Resource Room. • Note that you could repeat this activity when covering the chapter on Magnetism 6 • If you are making electromagnets remember that you must use enamelled wire which is insulated and prevents the current simply running along the top of all the wires. The sections should be sanded however to remove this insulation material for connection. • The textbook suggests using batteries but these run down very quickly so I would use power-packs instead. Precautions when using power-supplies 1. It must be direct current (d.c.). 2. Keep the voltage fairly low. 3. Notice that the electromagnet gets stronger (and the wire heats up) as the voltage is increased. This is because the power supply is producing a larger current which in turn has a larger magnetic field associated with it. 4. These power-packs are fairly robust and the greatest danger with them here is that they will heat up the wire which may cause burning. 5. The fuse in the power-supply will ‘trip’ if the voltage is too high so try to ensure the voltage is kept below this value. 5.3 light to electrical to kinetic Solar panel connected to an Electric Motor There should be one or two of these available in the Energy Resource Box, and I have another one in my lab. 6. Syllabus: Give examples of energy conversion from everyday experience. • Stress the idea that electrical energy is the most useful because it can be converted relatively easily to all other forms. • Ask students to learn examples of electric to sound (a speaker), electric to heat (a kettle), electric to light (light-bulb), electric to kinetic (a motor) etc. • Ask each student to bring in something which contains energy / demonstrates an energy conversion and have a prize for the best/most origianl idea. Confusion with the terms “Potential” and “Kinetic” energy It’s not surprising that this causes confusion. The tendency in many text-books (and indeed exam papers) is to divide energy into categories like potential, kinetic, sound, heat etc., when in fact potential energy and kinetic energy are more like umbrella terms, i.e. you could say that all energy is either potential or kinetic. Examples of Kinetic energy are sound and heat because they involve the movement of molecules. Examples of Potential energy would be a stretched string, or perhaps an electrical battery.