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full17 ch. sc notes
Chapter 17 SC notes
| Question | Answer |
|---|---|
| any material that attracts iron or materials containing iron | magnet |
| one of two points that have opposing magnetic properties | magnetic pole |
| the force of attraction or repulsion generated by moving or spinning electric charges | magnetic force |
| When is magnetic force present? | when poles come near each other |
| Where does a magnetic field exist? | where magnetic forces can act |
| How does the spacing of the magnetic field lines tell you about the strength of the magnetic field? | the closer the lines, the stronger the field |
| How are electrons involved in magnetized objects? | electrons induce the magnetic field and the atom then has a north and a south pole |
| Why are not all materials magnetic? | individual atoms cancel each other out, domains do not line up |
| What is a domain? | a group of atoms in an area |
| What makes a material magnetic? | the north and south poles of all the domains are aligned and make a magnetic field, thus creating its magnetism |
| How can an object be demagnetized? | when the domains shift or unalign |
| How can you make an object into a temporary magnet? | rub one pole of a magnet against another object to make the domains align |
| If you cut a magnet, why do you always end up with a new north and south pole? | the domains align, since magnets have aligned domains in the first place |
| What are ferromagnets? | magnets made of iron, nickel, cobalt, and have strong magnetism |
| What is an electromagnet? | a magnet made of electric currents, which usually have iron cores |
| What are two characteristics of temporary magnets? | easy to magnetize, easy to lose |
| Who came up with the theory of why magnets point north? | William Gilbert |
| What was his theory? | magnets point north because Earth is one big magnet, and the poles are sideways |
| What will happen if a compass is placed on top of a magnet? | the needle will point south |
| Why are auroras seen at the poles? | the magnetic field is the strongest there, particles get pushed |
| Who discovered the relationship between electricity and magnets? | Hans Christian Oersted |
| What did Oersted find? | the direction of magnetic field depends on the direction of the current |
| In Figure A in the related Powerpoint, if no electric current exists, what happens to the compass needles? | they all point in the same direction |
| What is the electric current goes right (blue) to left (red)? | the compass needles deflect in clockwise direction |
| the interaction between electricity and magnetism | electromagnetism |
| a coil of wire that produces a magnetic field when carrying an electric current | solenoid |
| made up of a solenoid wrapped around an iron core | electromagnet |
| What makes electromagnets so strong? | the domain in the iron line up, and the solenoid and core fields make the overall field very strong |
| Why can electromagnets be turned on an off? | a solenoid has a field only when electric current runs inside of it |
| a device that changes electrical energy into mechanical | electric motor |
| How are voltage and current related? | inversely related |
| What are the parts of an electric motor? | energy source, armature, permanent magnet |
| a device that measures current, has an electromagnet between the poles of a permanent magnet | galvanometer |
| What did Faraday discover? | magnetic fields could induce electric current |
| What was his experiment? (see Figure.) | he tried to make the magnetic field of an electromagnet induce electric current in a second wire |
| What were his results? | the galvanometer moved only when there was a change in the magnetic field |
| the process by which an electric current is made by changing a magnetic field | electromagnetic induction |
| a device that uses electromagnetic induction to change mechanical energy into electrical | electric generator |
| In an electric generator, is the current DC or AC? | AC; the current changes when the coil makes a half turn (see Figure) |
| a device that increases or decreases voltage of AC | a transformer |
| What are the effects of a step-up transformer and a step-down? (see Figure) | the voltage increases, decreases current; and vice versa |
| How does the energy change after being subject to a transformer? | it doesn't; the energy stays the same |
| How many times is electric current transformed for houses? | 3 step-downs |
| The marked end of a compass needle always points directly to? | a magnet's south pole |
| When a current-carrying wire is placed between two poles of a magnet, the wire jumps up (see Figure), why? | the wire creates a magnetic field that interacts with the magnetic field of the magnet |
Created by:
Tsarmina
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