Upcoming SlideShare
×

# Magnetism physics

2,511 views
1,999 views

Published on

5 Likes
Statistics
Notes
• Full Name
Comment goes here.

Are you sure you want to Yes No
• Be the first to comment

Views
Total views
2,511
On SlideShare
0
From Embeds
0
Number of Embeds
12
Actions
Shares
0
208
0
Likes
5
Embeds 0
No embeds

No notes for slide

### Magnetism physics

1. 1.  A magnet is a materialor object that produces amagnetic field with aNorth and South Pole.Magnetism: an invisibleforce that pushes or pullsmagnetic material.
2. 2. HISTORYOFMAGNETS
3. 3.  Regions of atoms that have the same magnetic polarity (N/S Alignment). Mini-magnets. Unmagnetized Iron  Magnetic domains point in different directions.  Magnetic fields cancel each other out. Magnetized Iron  Magnetic domains are lined up in the same direction  Magnetic fields amplify each other.
4. 4. The direction of the magnetic force is from NORTH to SOUTH
5. 5. TWO UNLIKE POLES GIVE A TWO LIKE POLES FORCE OF ATTRACTION TOGETHER WILL HAVE A FORCE OF REPULSIONCan you explain what the lines of force show?Where is the strongest part of the field?Where is the weakest part of the field?
6. 6. Small particles of iron filings are pushed into patterns bya magnetic field. If we sprinkle iron filings on a piece ofpaper over a magnet we can see...The lines of force are veryclose together here – the fieldis very strong.The lines of force are furtherapart here – the field is weaker.A line of force links one pole of a magnet to the other pole.
7. 7. FOR EACH PICTURE IDENTIFY THE FORCEILLUSTRATED……………A) B)
8. 8. MAGNETIC COMPASSCONTAINS A MAGNETTHAT INTERACTS WITHTHE EARTHS MAGNETICFIELD AND ALIGNS ITSELFTO POINT TO THEMAGNETIC NORTH ANDSOUTH POLES.
9. 9. North magnetic pole located atsouth geographic pole South magnetic pole located atnorth geographic pole.
10. 10. Magnetic declination •is the angle between magnetic north and geographic true north. •Angle varies by location •Ranges from 0⁰ to 25 ⁰
11. 11. Electromagnet coil of wire that acts as a magnet when an Electric current is passed through it. stops being a magnet when the current stops. Often, the coil is wrapped around a core of ferromagnetic material like steel, this enhances the coils magnetic field.
12. 12. an object made from amaterial that is magnetized &creates its own persistent magnetic field. Example refrigerator magnet
13. 13.  Levitating trains (MagLev) Treatdepression & chronic headaches Electric motors Stereo Speakers Credit Cards
14. 14. •Produced by electric currents•Defined as a Region where magnetic forces can be detected.•Has a North & South magnetic pole•The SI unit for a large magnetic field is the Tesla•The SI unit for a smaller magnetic field is the Gauss•(1 Tesla = 10,000 Gauss).
15. 15. The strength of a magnetic field (B) isrelated to the amount of magnetic force (F)that is applied to a moving test charge whenit is at a given location in the field. B = F magnetic qvq = test charge magnitudev = speed of the charge
16. 16. A proton moving east experiences an upward force of 8.8 x10-19 N due to the Earth’s magnetic field. The field has astrength of 5.5 x 10-5 Teslas (T) to the north.Find the speed of the proton.q = 1.60 x 10-19 C B = FmagneticB = 5.5 x 10-5 T qvFmagnetic = 8.8 x 10 10-19 N v = Fmagnetic qB Fmagnetic = qvb SinѲ
17. 17. Solutionv = 8.8 x 10-19 N (1.60 x 10-19 C) (5.5 x 10-5 T) 1.0 x 10 5 m/s
18. 18. The direction of the magnetic force is perpendicular to the plane of the magnetic field and to thedirection of the charge. USE THE RIGHT HAND RULE!!!
19. 19. Current carrying wires that are placedin a magnetic field also experience amagnetic force. I – CURRENT F- FORCE WIRE
20. 20. The magnitude of the magnetic force canbe written in terms of the current (I)flowing through the length of the wire (L).Magnetic Force in a Current Carrying wire F = BIL
21. 21. A 10.0 m long power line carries a current of 20.0 Aperpendicular to the Earth’s magnetic field of5.5 x 10 10-5 T.What is the magnetic force experienced by the powerline?I = 20.0 AB = 5.5 x 10 10-5 TL = 10.0 m F = BIL F = (5.5 x 10 10-5 T)(20.0 A)(10.0 m) = 0.011 N
22. 22. Charges that are in motion (an electrical current)produce magnetic fields. Magnetic field moves around a wire with a current in a circular fashion. Which direction???
23. 23. Right Hand Rule1. Thumb goes in thedirection of the current.2. Fingers wrap around wirein the direction of themagnetic field.
24. 24. Arranging wire in a coil and running a currentthrough produces a magnetic field that is similar to a bar magnet.
25. 25. • A coil woundinto a tightlypacked helix.•Produces auniformmagnetic fieldwhen a chargeis applied to it.
26. 26. 1. A particle with a positive charge of q moves with a speed v and passes through a magnetic field B parallel with the speed v. What is the magnitude of the magnetic force on the particle? a) F = qvB b) F = -qvB c) F = 0 d) F = qvB/2 e) F = -qvB/2 2. In the figure below, a magnetic field of .01 T is applied locally to a wire carrying a current of intensity I = 10A. What is the magnitude of the magnetic force applied to the wire? a) F = .3N b) F = .4N c) F = .5N d) F = 1N e) F = 3N
27. 27.  A wire 36 m long carries a current of 22A from east to west. If the maximum magnetic force on the wire at this point is downward(toward Earth) and has a magnitude of 4.0 X 10-2 N, find the magnitude and direction of the magnetic field at this location. Given: l = 36 m I = 22A Fmagnetic = 4.0 X 10 -2 N Unknown: B = ??? Fmagnetic = B ∙ I ∙ l then B = Fmagnetic Il B=
28. 28. 1. A particle with a positive charge of q moves with a speed v and passes through a magnetic field B parallel with the speed v. What is the magnitude of the magnetic force on the particle? a) F = qvB b) F = -qvB c) F = 0 d) F = qvB/2 e) F = -qvB/2 Solution: c) The force F, on the charge q moving with a velocity v in a magnetic field b is F = q(v x B). The magnitude of F is F = q·v·B·sinθ where θ is the angle between v and B. In our case the v and B vectors are parallel, so sinθ = 0. In conclusion F = 0.2. In the figure below, a magnetic field of .01 T is applied locally to a wire carrying a current of intensity I = 10A. What is the magnitude of the magnetic force applied to the wire? a) F = .3N b) F = .4N c) F = .5N d) F = 1N e) F = 3N Solution: b) The magnitude of a magnetic force applied to a current-carrying wire situated in a magnetic field is F = I·B·l·sinθ where: · l is the length of the wire, · B is the magnetic field strength · I is the current in the wire, · θ is the angle between the wire and the magnetic field. In our case sinθ = 4/l so l·sinθ = 4m. F = 10A·.01T·4m = .4N
29. 29.  A wire 36 m long carries a current of 22A from east to west. If the maximum magnetic force on the wire at this point is downward(toward Earth) and has a magnitude of 4.0 X 10-2 N, find the magnitude and direction of the magnetic field at this location. Given: l = 36 m I = 22A Fmagnetic = 4.0 X 10 -2 N Unknown: B = ??? Fmagnetic = B ∙ I ∙ l then B = Fmagnetic Il B = 4.0 X 10-2 N = 5.0 X 10-5 T (22A)(36m)