Agenda This Week –Ch –Skip Lab, No Quiz Next Week –Finish 29, No Quiz –Review Following –Exam II on Monday (2 weeks) –April 6 th [Or previous Friday if prefer] Sections – – –

Cross Product Hint: Google it! Multiply along arrows Positive Values I,j,k  direction unit vectors

Cross Product Multiply along arrows Negative Values

Cross Product a x b = 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! e-e-

X X X XX X X X X X X X X X X XX X X X 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 (F C = ma c = mv 2 /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. Source (Velocity Selector ) d1 d2 = 2 x d1 DET#1

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) X X L/10 2L/3 L L/3

X X 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! X X e-e-