Where is the magnetic field strongest?
School blocks YouTube? Use file below.
St. Mary's U. Astronomy & Physics Dept.
B) Magnetic Fields - regions in space where a magnetic forces may be detected
Magnetism
David Colarusso, Youtube
We will focus on fields around:
1) current carrying wire
2) permanent & electromagnets
3) Bar Magnets
A Magnetic Field is Curved
A magnetized needle moving near a magnet
Magnetic lines of force of a bar magnet shown by iron
filings on paper:Magnet
from
Practical Physics, publ. 1914 by
Macmillan and Company - copyright expired
(Actual magnetic fields contain
many more lines of
magnetism)
Solar Flames are deflected by
the suns magnetic field
1. Magnetic flux lines - lines of magnetism in a magnetic field.
- magnetic field is not continuous.
Between each line of magnetism
there exists ....
... no magnetic field
a) The needles of a compass line up perfectly with the flux lines
b) The arrows on a flux line show where the North Pole of a compass would point in that field.
Source Unknown
Compass / Bar Magnet
Windows
to the Universe
| Flux Arrows point
"OUT of NORTH, INTO SOUTH" and back over again to North |
c) Magnetic force strongest at the ...
At Poles ...
... where flux lines are closest.
Cutting Magnets ...
... each piece is a brand new magnet
How can magnets
attract non-magnets?
St. Mary's Physics YouTube Channel
Directions: Slide the magnet on the right over to the metal on the left. (unmagnetized metal on left)
Certain metals contain magnetic regions called
domains.
They are randomly orientated.
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The magnetic field in the bar magnet reorient the random magnet domains in the metal |
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Ex) Which diagram best represents magnetic flux lines around a bar magnet?
Flux lines don't cross, Out of North into South
d) Measuring the strength of a magnetic field
Put a wire with a known current into the field and measure the force on the wire
Where does the north pole
of a
compass point south?
Earth's Magnetic Field
Windows to the Universe
What are these magnetic lines called?
Where is the field strongest?
Mina Gong - Class of 2009
Flux lines, The field is strongest at the poles
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