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# 8th Grade Science - Unit 8.3 Forces at a Distance - Study Guide **1. Magnetism:** * This unit was about magnetism, a non-contact force. * Magnetism is created by electrons moving in the same direction. * Iron, Nickel and Cobalt are the only metals that can be magnetized. **2. Magnetic Fields:**...

# 8th Grade Science - Unit 8.3 Forces at a Distance - Study Guide **1. Magnetism:** * This unit was about magnetism, a non-contact force. * Magnetism is created by electrons moving in the same direction. * Iron, Nickel and Cobalt are the only metals that can be magnetized. **2. Magnetic Fields:** * Magnets are completely surrounded by magnetic fields. * Magnetic field lines move from north to south. * The magnetic field lines are the strongest at the poles. * Earth is surrounded by a magnetic field. **3. Earth's Magnetic Field:** * The study of Earth's magnetic field is called GEOMAGNETISM. * Earth's magnetic field is created by Earth's molten iron core. * Earth's magnetic field changes polarity every few hundred thousand years. **4. Compass:** * A compass works due to its magnetized needle that always points to the magnetic south pole. **5. Magnetic Poles:** * The magnetic South Pole is found near the geographical North Pole. * The magnetic North Pole is found near the geographical South Pole. **6. Potential and Kinetic Energy:** * In a magnetic field, we increase Potential Energy by going against the magnetic Force. * A magnetic force wants to pull attracting poles closer together. * A magnetic force wants to push repelling poles further apart. * Breaking a magnet in half will create 2 magnets with both north and south poles. * Magnetic forces fall within Newton's laws of Force and Motion. * In a magnetic field, Potential Energy is increased by going against the Magnetic Force. * In a magnetic field, Potential energy is mostly transferred into Kinetic energy. **7. Energy:** * Energy cannot be created nor destroyed, this applies across the entire universe. **8. Electromagnetism:** * Electromagnetism is the relationship between Electricity and Magnetism * Electromagnets are created by running an electric current through a coil * Electromagnets can be turned on and off, increase its magnetic field, change polarity * Electromagnets have the same magnetic field properties as magnets * Trains or any vehicle levitated by electromagnetism is not exposed to friction * Several everyday items use electromagnets or magnets such as doorbells, electric vehicles, cell phones, computer hard drives, electric motors, compass, **9. Battery:** * A battery stores chemical energy that will be converted into electrical energy * A battery has 3 main parts: anode, cathode and electrolyte. **10. Electric Circuits:** * In order to run an electric current the circuit must be in a closed loop. * A transformer in a power grid converts high voltage to usable voltage. **11. Scientific Tests:** * In Scientific Tests the Independent variable is what you change. * In Scientific Tests the dependent variable is the outcome, result or what you want to measure. * In Scientific Tests the controlled variable is what stays the same. * In Scientific Tests there should only be one independent variable.