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# fe x x1 0 physics 2b summer session

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Unformatted text preview: v ˆ = ma = m ( − r ) r + ˆ FB = qvB0 ( − y ) + + 2 + Physics 2B - Summer Session 2 - C. Palmer August 21, 2013 29 y   The acceleration is always toward the center. z x   Circular   If motion is not perpendicular to the field, then part of the motion is not impacted by the force.   It will be a helix. ˆ FB = qv⊥ B0 ( − y ) v ˆ = ma = m ( − r ) r 2 ⊥ Physics 2B - Summer Session 2 - C. Palmer August 21, 2013 30   We now have a very interesting relationship y between several of the key variables. z + + + 2 v qvB0 = m r x + Physics 2B - Summer Session 2 - C. Palmer August 21, 2013 31 For an electron (me, -e) with velocity, v=3e5m/s, perpendicular to a uniform magnetic field, B0=4T, in which it is immersed, what is the radius of its circular motion? Recall me=9.1e-31 kg and e=1.6e-19 C. A)  2.3 Mm B)  23 Mm C)  0.43 µm 2 v qvB0 = m r D)  43 nm Physics 2B - Summer Session 2 - C. Palmer August 21, 2013 32 For an electron (me, -e) with velocity, v=3e5m/s, perpendicular to a uniform magnetic field, B0=4T, in which it is immersed, what is the radius of its circular motion? 2 Recall me=9.1e-31 kg and e=1.6e-19 C. A)  2.3 Mm B)  23 Mm C)  0.43 µm D)  43 nm v qvB0 = m r mv ⇒r= qB0 Physics 2B - Summer Session 2 - C. Palmer August 21, 2013 33 y   The acceleration is always perpendicular to motion. F ⋅ ds + + + + W =∫ z x Physics 2B - Summer Session 2 - C. Palmer August 21, 2013 34 The acceleration is always perpendicular to motion. What is the work done by a MAGNETIC field on a charged particle? + and the field strength. B)  It is 0 for a uniform B field. C)  It is always 0. + + A)  It depends on the charge W = ∫ F ⋅ ds + Physics 2B - Summer Session 2 - C. Palmer August 21, 2013 35 The acceleration is always perpendicular to motion. What is the work done by a MAGNETIC field on a charged particle? + and the field strength. B)  It is 0 for a uniform B field. C)  It is always 0. + + A)  It depends on the charge W = ∫ F ⋅ ds + Physics 2B - Summer Session 2 - C. Palmer August 21, 2013 36   A mass spectrometer is a clever device that uses both electric and magnetic fields to determine information about the properties of individual particles.   These are typically used to determine the composition of complicated molecules.   The first step is to breakdown the molecule into ions for individual analysis. Physics 2B - Summer Session 2 - C. Palmer August 21, 2013 37 Mass Spectrometer Part 1: Velocity Selector What directions are the electric and magnetic forces? A)  FB in +x; FE in +x B)  FB in +x; FE in –x C)  FB in –x; FE in +x D)  FB in –x; FE in –x y z x Physics 2B - Summer...
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## This note was uploaded on 09/10/2013 for the course PHYS 2B 2b taught by Professor Hirsch during the Summer '10 term at UCSD.

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