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Magnetism, Ch. 8
Magnetism, Ch. 8; Glencoe text, Physical Science
| Question | Answer |
|---|---|
| The first recorded observation of magnetism was when? | 2,000 years ago the Greeks discovered deposits of a mineral that attracted chunks of iron. |
| What is magnetism? | Magnetism refers to the properties and characteristics of a magnet. |
| What surrounds a magnet? | magnetic field |
| What is a magnetic field? | It surrounds a magnet and exerts a force on other magnets and objects made of magnetic material. |
| What are the characteristics of magnetic fields? | magnetic fields surround magnets, are designated by lines of force, are stronger closer to the magnet and weaker farther away from the magnet. They also have direction. |
| How do magnets interact? | like magnetic poles repel each other while opposite poles attract one another. |
| Which way would a compass needle point if Earth's magnetic poles switched places? | toward the south magnetic pole in the southern hemisphere |
| What occurs when two magnets are brought close together? | When two magnets are brought close together, their magnetic fields combine to produce a new magnetic field. |
| What are magnetic domains? | Groups of atoms with aligned magnetic poles. |
| What did Oersted hypothesize? | He hypothesized that the electric current must produce a magnetic field around the wire, and the direction of the field changes with the direction of the current. |
| What is an electromagnet? | An electromagnet isa temporary magnet made by wrapping a wire coil carrying a current around an iron core. |
| What is a solenoid? | A solenoid is a single wire wrapped into a cylindrical wire coil. |
| What are the properties of electromagnets? | Electromagnets are temporary, their strength is dependent on how many turns of the wire there are and the current. Electromagnets also have poles and will align itself with the lines of a magnetic field, and can attract or repel other magnets. |
| What is an electric motor? | A device that changes electrical energy into mechanical energy. |
| What is a galvanometer? | Devices that use an electromagnet to measure electric current. |
| Explain why it is necessary to continually reverse the direction of current flow in the coil of an electric motor. | When an end of the coil moves past a pole of the permanent magnet, reversing the current causes the end of the coil to be attracted to the other pole of the permanent magnet. Repeating this process keeps the coil rotating in the same direction. |
| What is a simple electric motor? | It is an electromagnet that rotates between the poles of a permanent magnet. |
| Describe two ways you could change the strength of the magnetic field produced by an electromagnet. | by varying the electric current passing through it or by changing the number of loops |
| What is electromagnetic induction? | The generation of a current by a changing magnetic field. |
| What is a generator? | A generator uses electromagnetic induction to transform mechanical energy into electrical energy. |
| What is a turbine? | It is a large wheel that rotates when pushed by water, wind, or steam. |
| What is direct current? | Direct current flows only in one direction through a wire. |
| What is alternating current? | Alternating current reverses the direction of the current in a regular pattern. |
| What is a transformer? | It is a device that increases or decreases the voltage of an alternating current. |
| Explain why the output voltage from a transformer is zero if a direct current flows through the primary coil. | Only an alternating current induces the voltage int the transformer. |
Created by:
RayRamirez
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