Magnets & Magnetic materials LO: To identify magnetic materials and devise a method to determine the strongest magnet SC: 1. describe permanent magnets as examples of non-contact forces. 2. identify magnetic materials. 3. to make a paperclip magnetic and explain using a ‘model’ to explain why it is magnetic Lesson 1 Stronger Magnetic Field S N How could I find out who has the strongest magnet? Bar Magnets Magnetic materials A magnetic material is attracted to a magnet. Only iron (Fe), nickel (Ni) and cobalt (Co) are magnetic. Ag 1 7 of 20 29 2004 © Boardworks Ltd 2005 How could you turn a piece of iron into a magnet? S N Draw and label the points of a compass. Earth – a Giant Magnet Animation Do you think screwdrivers should be magnetic? Why? Lines of Magnetic field Lesson 2 Lines of Magnetic field LO: To understand that magnetics have lines of magnetic field to and from the poles. SC: 1. show lines of magnetic field using iron filings and plotting compasses. 2. draw lines with arrows to show the magnetic field lines around magnets 3. can predict the lines of magnetic field when 2 magnets are attracting or repelling each other. What is a magnetic field? The region around a magnet where it has a magnetic effect is called its magnetic field. When a magnetic material is placed in a magnetic field it will experience a force. S N The iron filings feel the effect of the magnetic field and show the direction of the forces in this region. 1 16ofof20 29 2004 © Boardworks Ltd 2005 Shape of a magnetic field What is the shape and direction of the lines of force in the magnetic field around a bar magnet? strongest field at poles N S strongest field at poles weakest field further away from poles Where is the magnetic field strongest? 1 17ofof20 29 2004 © Boardworks Ltd 2005 Viewing magnetic fields: N poles together Bring the north poles of two bar magnets together. S N N S What happens to the magnets? Next, bring the two north poles as close to each other as possible and place a piece of paper on top of the magnets. Carefully scatter iron filings onto the paper. Draw the pattern created by the iron filings. 1 18ofof20 29 2004 © Boardworks Ltd 2005 Magnetic field pattern: N and S poles together What do you notice about the pattern of the lines of force in the region between the north and south poles? S N S N How does this pattern compare with the pattern between the two north poles? 1 19ofof20 29 2004 © Boardworks Ltd 2005 Magnetic field pattern: N poles together What do you notice about the pattern of the lines of force in the region between the two north poles? S 1 21ofof20 29 N 2004 © Boardworks Ltd 2005 Where can you find evidence of the magnetic field on earth? Yr 8 APP – AF 1 Thinking Scientifically AIM We are learning about how science uses models to explain our world, and how scientists collect evidence to help support or change these models. Levels 3 & 4: Levels 5 & 6: Levels 7 & 8: Be able to use and recognise scientific ideas, and use evidence to back-up or deny a claim. Use and apply models to explain observations. Be able to use models, and recognise their strengths and weaknesses. Explain how evidence and creative thinking is used in the development of scientific ideas and models. Describe how the scientific community are involved in deciding the value of new ideas in science. Be able to apply models from different areas of science to explain observations and findings. Explain how peer review is used to check new ideas in science. Understand how evidence is used in science to develop new www.appinscience.com ideas and models. Yr 8 APP – AF 1 Key language linked to AF 1 Science is based around the gathering of evidence which is used to test scientific ideas and models. Evidence: The findings of scientific experiments and surveys. Model: A scientific way of showing or representing how or why things happen. Processes: A series of actions or changes. Phenomena: An occurrence that can be observed in some way. www.appinscience.com Yr 8 APP – AF 1 Key language linked to AF 1 Definitive Precise. The final decision. Scientific community Scientists across the world make up the scientific community. Scientists are grouped according to the area of science that they study, e.g. nuclear scientists, ecologists, nano technologists. Peer review The process by which a scientist’s new findings are checked by other scientists before they are published in scientific journals. Systematic Orderly. Carried out in a step-by-step way. www.appinscience.com Peer Review Checking new scientific ideas: What exactly is peer review? www.appinscience.com The Peer-review Process These people are all science experts http://undsci.berkeley.edu/images/us101/peerreview.gif www.appinscience.com Models What exactly is a model? www.appinscience.com Scientific Models Scientific Models: A scientific way of representing how or why things happen. Examples: • States of matter • The cell as a building block for life • Electricity is charge flowing along a wire www.appinscience.com Models in explanations Models help explain things… www.appinscience.com The Model of Magnetism Magnets attract magnetic materials to them. They create a non-contact force called magnetism. Our model for magnets says that they have a North and a South pole. Magnets have an effect around them called a magnetic field. Our model for magnets shows the field as lines of force. www.appinscience.com Models in explanations How Compasses Work Pole Magnetism Our model for how compasses work imagines that the Earth acts like a big bar magnet. Our model says that magnetic force attracts magnetic materials. A compass is a tiny magnet. Its North pole points North as the imaginary bar magnet inside the Earth has its South pole at the Earth’s North pole. www.appinscience.com The Mystery of the Bermuda Triangle In the last 200 years, thousands of boats, ships and aircraft have come to grief in the Bermuda Triangle. Most of them have reasonable explanations, but 100’s of them remain unexplained. Can we use a scientific model to explain the mystery disappearances? www.appinscience.com Lost ships In 1642, Christopher Columbus sailed through the area of the Bermuda Triangle. He reported lights in the sky, and mentioned that his compass stopped pointing North. In a second trip he lost ten ships in a hurricane. Many ships have since disappeared completely, or been found adrift with their crew missing. In 1918 the US Navy ship the Cyclops vanished without a trace. It had a crew of 300, and weighed 17,500 tons. The crew sent no emergency radio message. www.appinscience.com Lost Planes On December 5th 1945, 5 US Navy bombers disappeared without a trace, along with their search plane. The last transmission from Lieutenant Taylor said that both his compasses had stopped working. No sign was ever found of flight 19- the aircraft and the 27 airmen disappeared. Many planes have been lost. Others have reported strange experiences: “The sea frothed up below me”. “I became obscured by fog. The compass spun wildly”. “All of our radio and communications equipment failed”. www.appinscience.com Watch the film and write down your theory Can you use a model to explain your theory? www.appinscience.com The theories Many theories have been put forward to explain the mystery of the Bermuda Triangle: 1. There is no mystery: Planes and ships are always being lost at sea everywhere. They are due to bad weather, mechanical failure or human error. 2. The strange weather model: Warm damp air rises into the atmosphere and condenses to form massive storm clouds with hurricane strength winds. 3. Freak waves: Undersea Earthquakes and landslides cause giant tidal waves that swamp ships. 4. Aliens and Atlantis: Ivan T Anderson suggest that the ships, aircraft and their occupants have been abducted by aliens and taken to Atlantis. 5. Strange magnetic fields: Underground magnetic rocks make compasses point away from the Earth’s North pole. These magnetic anomalies may also be caused by magma flowing near the Earth’s surface or by electrical storms. Models in explanations Strange magnetic fields: Underground magnetic rocks make compasses point away from the Earth’s North pole. These magnetic anomalies may also be caused by magma flowing near the Earth’s surface or by electrical storms. Magnetic rocks, surface magma and electrical storms all distort the magnetic field lines like an iron lump near a magnet. www.appinscience.com Methane bubbles Dr May and Dr Monaghan published a scientific paper that showed that huge bubbles of gas rising from the sea bed could cause ships to sink when they burst at the surface. The ship falls into the hole caused by the bubble. The bubbles could also cause explosions, and possibly cause strong magnetic fields. No-one however has observed a methane bubble in the world’s oceans. There are large amounts of methane hydrates under the oceans. When the pressure on methane hydrate is reduced, methane gas is released. www.appinscience.com Explaining the Bermuda Triangle So what causes the ships and planes to go missing in the Bermuda Triangle? 1. List the different scientific models that can be used to explain the disappearances within the Bermuda Triangle. 2. Describe your most likely explanation for the mysterious disappearances. 3. How would you share a new model to explain the mystery of the Bermuda Triangle with other scientists? www.appinscience.com Thinking Scientifically: Reporting a new disappearance in the Bermuda Triangle A ship and a search and rescue plane have gone missing within the Bermuda Triangle. You work for a National newspaper - and your task is to write a front page article about the disappearance. In your article you must explain: • What is the Bermuda Triangle? • What are the possible scientific explanations and models that could explain it? Be sure to mention how science is unsure about the possible causes of such disappearances, and how new ideas are checked before the scientific community will accept them. Electromagnets Lesson 3 Electromagnets LO: To explain how a coil of wire can become magnetic so making an electromagnet. SC: 1. can show that a current flowing through a wire is magnetic 2. can explain the difference between permanent magnets and electromagnets. 3. can explain the uses of some electromagnets. 02/07/2019 Magnet: Solenoid: N S Electromagnets 02/07/2019 The strength of an electromagnet can be increased by doing three things: 1) Increasing the voltage 2) Increasing the number of coils 3) Inserting an iron core (The poles can be reversed by reversing the direction of the current) Examples of electromagnets 02/07/2019 1. Speaker 2. Relay switch 02/07/2019 Uses of electromagnets 2 - An electric bell Looking at data Lesson 5 Yr 8 APP – AF5c Electromagnet Strength AIM Use data to describe and explain the relationship of the voltage and the strength of an electromagnet. Cameron wanted to make an electromagnet that would pick up about 50 paperclips at a time. Use the results shown to work out - The average - The pattern and describe the relationship between the two variables - Scientific ideas to explain your conclusion - How the data could be improved and suggest improvements. Improving data How many paperclips can an electromagnet pick up? Choose ways in which the data below could be improved: Repeat the measurements Use a bar chart Take a measurement every one volt State the number of coils Use a data-logger Quality of data sources Can you make an electromagnet that lifts 50 paperclips? How could this data be improved? Discuss what pupils could do to improve it. Voltage (V) Number of paperclips picked up Average number of paperclips Repeat 1 Repeat 2 Repeat 3 2 1 1 1 1 4 11 15 10 12 6 17 18 23 19 8 37 38 28 34 10 wire too hot wire too hot wire too hot Reliability of Data Read how pupils gathered evidence for the strength of an electromagnet. Put them in order of reliability. Discuss your decisions. A. On the lowest voltage, switch the power on and record the number of clips lifted. Increase the voltage by 2V, repeat. Once 10V is reached, start again and repeat 3 times. B. On the lowest voltage, switch the power on and record the number of clips lifted. Repeat 3 times, then increase the voltage by 2V, repeat 3 times and so on. C. On the lowest voltage, switch the power on and record the number of clips lifted. Increase the voltage by 2V, up until 10V. The graph was plotted, but only if a point looked anomalous was it repeated . Revision Lesson 7 Forces between magnets – experiment 1 60ofof20 29 2004 © Boardworks Ltd 2005 The Odd One Out?
