www.BZUpages.com Magnetic Field Presented to Sir Tariq bhati By M.Aatif Aneeq 0715
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Magnetic Field
Presented to Sir Tariq bhatiBy M.Aatif Aneeq
0715
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Magnet
Observation of the magnetic properties of the mineral magnetite (Fe3O4) or Lodestone ( A
lodestone is a form of magnetite which demonstrates distinctive magnetic qualities.)
probably began several thousand years ago when early Greeks found naturally occurring magnets
attracted small pieces of iron.They people use magnet as compass needle about
1000 A.DChinese may have known about the north south
effect of a magnet much earlier.Magnet was found near the city of Magnesia.
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Magnetic force/field
Electric force F=qE on the charge q produced within the electric field E.Similarly for studying magnet we consider magnetic field B.Magnetic field is the vector field which exert force on the moving charges.
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Magnetic force/fieldWe take an example of Cathode Ray Tube. In which small magnet deflect the electron beam in cathode ray tube.
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Magnetic force/field
Demonstrate electron beam deflection by a magnetic field as a moving spot on the screen.
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Magnetic force/field
The deflecting force is always perpendicular to the velocity of the moving electrons.
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Magnetic force/fieldThe Magnetic field B is the vector field that exerts a force F on the charged particles
F = qv x B
Magnetic force to be exerted on a particle
•Must be Charged•Must be Moving
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Magnetic force/field
Direction of force by Right Hand Rule
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Magnetic force/field
F = | qvB sinθ |
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Magnetic force/fieldF = | qvB sinθ |
Where Sinθ = 90 = 1
Hence force F = qvB
The SI Unit of the Magnetic Field is (N/C) / (m/s)
Which is called tesla. T. Tesla is the large unit of Magnetic field.
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Magnetic force/field
As we know Force exerted on charge is Always perpendicular to the Velocity “V” ButWork done by this force is zero…
We know thatW= F.S
Work done in a small region dɭ will bedW=F. dɭ
As v = dɭ/dtdɭ = vdt
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Magnetic force/fielddW= F. Vdt
Since θ between F and V is 90 So cos 90 = 0
Therefore Work “W“ done by magnetic force is zero
Iron Filing Aligns with the field of a bar magnet
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