1. 21.2 Electromagnetism In 1820 Hans Oersted discovered how magnetism and electricity are ______________. A unit of measure of magnetic field strength, the _____________, is named after him. connected oersted

2. 21.2 Electromagnetism Electricity and Magnetism How can an electric charge create a magnetic field? How is an electromagnet controlled? How do galvanometers, electric motors, and loud speakers work?

3. 21.2 Electromagnetism Electricity and magnetism are different aspects of a single force known as the ________________ ____________. The electric force results from ___________ particles. The magnetic force usually results from the _______________ of _______________ in an atom. Electricity and Magnetism electromagnetic force charged motionelectrons

4. 21.2 Electromagnetism Magnetic Fields Around Moving Charges Oersted discovered an important physics principle… moving charges create a magnetic field Moving charges may be the _______________ charges that produce an electromagnetic wave or the moving charges in a ______________. Magnetic field lines form _____________ around a straight wire carrying a current. Electricity and Magnetism vibrating wire circles

5. 21.2 Electromagnetism If you point the thumb of your _________ hand in the direction of the current, your fingers _________ in the direction of the magnetic field. Electricity and Magnetism Direction of electron flow Direction of current Current-carrying wire Direction of magnetic field right curl

6. 21.2 Electromagnetism Forces Acting on Moving Charges A magnetic field exerts a force on a moving charge. Electricity and Magnetism Force deflecting the charge Velocity of charge A charge moving in a magnetic field is deflected in a direction ________________ to both the field and to the velocity of the charge. perpendicular

7. 21.2 Electromagnetism Forces Acting on Moving Charges A magnetic field exerts a force on a moving charge. Electricity and Magnetism A current-carrying wire in a magnetic field will be pushed in a direction _____________ to both the field and the direction of the current. perpendicular

8. 21.2 Electromagnetism Reversing the direction of the current will still cause the wire to be deflected, but in the _______________ direction. Electricity and Magnetism If the current is ______________ to the magnetic field, the force is zero and there is ____ deflection. opposite parallel no

9. 21.2 Electromagnetism If a current-carrying wire has a ________ in it, the magnetic field in the center of the loop points right to left ____________ the loop. Solenoids and Electromagnets loop through

10. 21.2 Electromagnetism Multiple loops in the wire make a __________. The magnetic fields of the loops ___________ so that the coiled wire acts like a ______ magnet. Solenoids and Electromagnets coil combine bar

11. 21.2 Electromagnetism The field through the center of the coil is the _______ of the fields from all the turns of the wire. Solenoids and Electromagnets A coil of current- carrying wire that produces a magnetic field is called a ______________ sum solenoid

12. 21.2 Electromagnetism If a ________________ material, such as an iron rod is placed inside the coil of a solenoid, the strength of the magnetic field ______________. Solenoids and Electromagnets The magnetic field produced by the current causes the iron rod to become a ____________. An ________________ is a solenoid with a ferromagnetic core. The current can be used to turn the magnetic field ____ and ____. ferromagnetic increases magnet electromagnet onoff

13. 21.2 Electromagnetism The strength of an electromagnet depends on… the ___________ in the solenoid the number of _________ in the coil the type of _________ The strength of an electromagnet can be ______________ using the following methods… Increase the current flowing through the solenoid. Increase the number of turns. Use cores that are _____________ magnetized. Solenoids and Electromagnets current loops core increased easily

14. 21.2 Electromagnetism Electromagnetic Devices Electromagnets can convert electrical energy into ___________ that can do __________. Common example: ______________ Electromagnetic devices such as galvanometers, electric motors, and loudspeakers change ________________ energy into ______________ energy. motionwork doorbells electrical mechanical

15. 21.2 Electromagnetism Galvanometers A galvanometer is a device that uses a solenoid to _____________ small amounts of current. A solenoid is attached to a ___________ and is free to rotate about an iron core. The solenoid is placed between the ________ of two permanent magnets. The greater the current, the more the solenoid _____________. Electromagnetic Devices measure spring poles rotates

16. 21.2 Electromagnetism A galvanometer uses an electromagnet to move a _____________. One common application is in an automobile _______ _____________. The wire is connected to a ____________ in the gas tank. Electromagnetic Devices pointer gasgauge sensor

17. 21.2 Electromagnetism Electric Motors An electric motor is a device that uses an electromagnet to turn an ____________. Electromagnetic Devices In this motor, a battery supplies current to a loop of wire through the _______________. axle commutator

18. 21.2 Electromagnetism When current flows through a loop of wire, the field of the permanent magnet ___________ one side of the loop. The other side of the loop is ____________. These forces rotate the loop. Electromagnetic Devices pushes pulled

19. 21.2 Electromagnetism Loudspeakers A loudspeaker contains a _____________ placed around one _________ of a permanent magnet. The current in the wires entering the loudspeaker changes direction and increases or decreases. Electromagnetic Devices solenoid pole

20. 21.2 Electromagnetism The magnetic force exerted by the permanent magnet moves the coil back and forth. As the coil moves, it causes a thin membrane to __________, producing sound ________ that match the original sound. Electromagnetic Devices Electrical energy converts to mechanical energy vibrate waves

21. 21.2 Electromagnetism Assessment Questions 1.A charged particle is moving across a plane from left to right as it enters a magnetic field that runs from top to bottom. How will the motion of the particle be changed as it enters the magnetic field? a.It will accelerate. b.It will deflect either up or down on the plane. c.It will deflect perpendicular to the plane. d.Its motion will not be affected. Force deflecting the charge

22. 21.2 Electromagnetism Assessment Questions 2.Which change will increase the strength of an electromagnet made by wrapping a conductive wire around an iron nail? a.reversing the direction of current flow b.replacing the nail with a wooden dowel c.increasing the number of coils of wire around the nail d.using a longer nail

23. 21.2 Electromagnetism Assessment Questions 3.A loudspeaker uses a magnet to cause which energy conversion? a.mechanical energy to magnetic energy b.electrical energy to mechanical energy c.electrical energy to magnetic energy d.mechanical energy to electrical energy

24. 21.2 Electromagnetism Assessment Questions 4. The motion of an electric charge creates an electrical field. True False Direction of magnetic field Direction of current Direction of electron flow