Transcript 21.1 Magnets & Magnetic Fields

```Assessment Questions 1-4
Magnetic review
 http://www.youtube.com/watch?v=uj0DFDfQajw&NR
=1&feature=fvwp
1. Besides a magnet what can
produce a magnetic field?
 A moving electric charge can create a magnetic
field = electricity flowing through a wire. LT#2
 We use moving magnets to generate an electric
current & we use electric current to make magnets.
 http://www.youtube.com/watch?v=9Zy0VHBXxL
U&annotation_id=annotation_397286&feature=iv
2. How is the magnetic field of an
electromagnet controlled?
 It can be turned on and off LT#2
 http://www.youtube.com/watch?v=UBiKruVV3a0
 It’s strength and direction can be controlled by
controlling the current.
 http://www.ehow.co.uk/video_4951982_doelectromagnets-work_.html
3. How are solenoids and electromagnets
used in galvanometers, electric motors and
loudspeakers?
 They all change electrical energy into mechanical
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

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energy. LT#1
http://www.youtube.com/watch?v=e5434dDB-7w
http://www.youtube.com/watch?v=it_Z7NdKgmY&fea
ture=PlayList&p=305357ACC216006C&playnext_from=
PL
Galvanometers detect electric current
A magnet and a wire coil are used to measure a
magnetic field caused by current.
Moving a magnet through the coil will deflect the
galvanometer = generator effect. LT#3
4. How does a ferromagnetic rod inside
a solenoid affect the strength of an
electromagnet? LT#2
 The rod makes the magnetic field much stronger.
 When current flows through the coil, it creates a
magnetic field that magnetizes the ferromagnetic rod.
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