Transcript Agenda

Agenda
• This Week
– Ch. 27-29
– Skip Lab, No Quiz
• Next Week
– Finish 29, No Quiz
– Review
• Following
– Exam II on Monday (2 weeks)
– April 6th [Or previous Friday if prefer]
• Sections
– 27.1-27.8
– 28.1-28.5
– 29.1-29.5
Cross Product
Hint: Google it!
I,j,k  direction unit vectors
Multiply along arrows
Positive Values
Cross Product
Multiply along arrows
Negative Values
Cross Product
axb=
Quick Solution for 2D or 3D problems
Cross Product
q(a x b) = q[
]
How Big Are B Fields?
• B Field units: Tesla (T)
– One T = 10,000 Gauss (G)
• Earth?
– ~ 0.5 Gauss = 0.5x10-4 T
• Fridge Magnet
– 10 Gauss = 1mT
• Largest Permanent Magnets
– ~ 5,000 Gauss = 0.5T [Rare Earth]
• Largest Electromagnetic Magnets
– ~ 10 T [Continuous]
– ~ 100T [Pulse]
– Superconducting special
Velocity Selector
• Create an instrument which allows only electrons with 1keV Energy
to Pass through. Can use E Field & B field
• Electric Force: F = qE
• Magnetic Force: F = q(vxB)
• Hint: Think Constant & Perpendicular
• What should E& B be? What direction?
• Design This!
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Mass Spectrometer
• Use magnetic Field to control which elements are counted by a
mass spectrometer.
• Hint: Keep E field in source/detector areas
– Use Circular motion (FC = mac = mv2/r)
– Start with this design
• Create a system that will measure C14 & C12 simultaneously with
two different detectors. Set up so ions enter analysis area with 1keV
of KE, and the detector #2 is 2x the distance of detector #1 for
maximum selectivity.
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d1
Source (Velocity Selector )
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d2 =X2 x d1
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DET#1
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DET#1
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Force on Current Carrying Wires
• Rank the total force felt by each of the following current carrying
wires. Each wire has an equal amount of current in the same
constant B field. Each Wire covers an equal “x” distance
• Hint: Plug in #’s if it helps
– #1: Straight Wire, distance 2L
– #2: Straight Wire (length L) + semicircle (radius r)
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2L/3
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L/10
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L/3
Velocity Selector
• Create an instrument which allows only electrons with 1keV Energy
to Pass through. Can use E Field & B field
• Electric Force: F = qE
• Magnetic Force: F = q(vxB)
• Hint: Think Constant & Perpendicular
• What should E& B be? What direction?
• Design This!
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