electromagnetismggggbbbbbbbbbbbbbbbb.pptx

Bbvv

1. Electromagnetism

2. -Electromagnetism results when electric currents and magnetic fields interact with each other . -In 1820, Danish physicist Hans Christian Oersted observed a magnet move in the presence of an electric current. -Oersted hypothesized that the electric current had produced a magnetic field. -He did more experiments with electricity and magnetism .He found that when a wire is carrying a current, a magnetic field is produced around the wire. What is electromagnetism?

3. How can you make a magnet using current? -An electric current in a single loop of wire produces a weak magnetic field. You can make a more powerful magnet by making a solenoid or an electromagnet .

4. -A coil of wire that carries an electric current, and therefore produces a magnetic field, is called a solenoid . -The more loops, the stronger the magnetic field . With a solenoid

5. -Wrapping a solenoid around an iron core makes an electromagnet . -This combination creates a more powerful magnetic field than the solenoid alone -Adding loops to the solenoid or increasing the electric current strengthens the electromagnet . With an electromagnet

6. What are some uses for electromagnets? -Electromagnets are useful for lifting and moving large metal objects containing iron. - When current runs through the solenoid coils, it creates a magnetic field that attracts the metal objects. -Turning off the current turns off the magnetic field so that the metal can be easily dropped in a new place. .

7. - Powerful electromagnets can raise a maglev train above its track. -Just as poles of a bar magnet repel each other, electromagnets in the train and track repel each other when the electric current is turned on What are some uses for electromagnets?

8. -A galvanometer is a meter that measures the strength and direction of an electric current in a wire . -A galvanometer contains an electromagnet between the poles of a permanent magnet. When current is applied to the electromagnet, the two magnetic fields interact and cause the electromagnet to turn. -The indicator, attached to the electromagnet, moves to one side of the zero on the scale, indicting the strength and direction of the current. What are some uses for electromagnets?

9. What are some uses for electromagnets? - Electromagnets are used in many devices that you may use everyday . Small electromagnets drive electric motors in objects from hair dryers to speakers. - A solenoid around an iron piston makes a doorbell rings .

10. How do motors work? An electric motor changes electrical energy into mechanical energy. Electric motors range in size from large motors, used to power Ferris wheels, to small motors used in computer cooling fans

11. - Electric motors are very similar to galvanometers as both contain an electromagnet that rotates between the poles of another magnet. However, in a motor, the electromagnet is made to rotate all the way around instead of back and forth in the magnetic field.

12. Electromagnetic Induction -Electric current can produce a magnetic field. In the early 1830’s,scientists wondered if the opposite is true. -English scientist Faraday connected a galvanometer to a wire coil. -When he moved a magnet back and forth inside the coil, the galvanometer needle moved, indicating current. Using a magnetic field to create an electric current in a wire is called electromagnetic induction

13. When electric charges move through a wire, the wire carries a current. Magnetic force from a magnet moving inside a coil of wire can make the electric charges in the wire move. When the magnet stops moving inside the coil, the electric current stops.

14. The electric current increases if you move the magnet through the coil faster or if you add more loops of wire . The current can also be induced by moving the coil over the magnet. An electric current is induced when you move a magnet through a coil of wire. The current increases if you move a magnet through the coil faster. The current also increases if you add more loops of wire.

15. What are some uses for induction? 1-To generate electricity -Electric generators use induction to change mechanical energy into electrical energy. -Many power plants use rising steam to turn the turbines. The steam is produced from burning fossil fuels or using nuclear reactions to heat water. Other sources of mechanical energy to turn turbines are blowing wind, falling water and waves. -Generators induce electric current when a magnet moves in a coil of wire or when a wire moves between the poles of a magnet. Did you know that most of the electricity that you use everyday comes from electromagnetic induction

16. Motor Generator Function The motor converts electric energy into mechanical energy The generator converts mechanical energy into electric energy It uses electricity It generates electricity