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Today, we delve into the fascinating dynamics of charged particles in magnetic fields, discussing essential principles such as the right-hand rule for direction, the forces at play, and the impact of crossed electric and magnetic fields. Join us as we analyze the effects of a magnetic field on a charged particle's motion, exploring fundamental relations like FE = qE and FB = qvB. This session also kicks off our new WebAssign and prepares us for an upcoming quiz. Get ready to enhance your understanding of charge motion and its real-world applications!
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Forces on Charges Spinning Around Again
Here we are again: • Today we will have a discussion about charge motion in magnetic fields and so some observations of wires in magnetic fields. • There is A new WebAssign (Aren’t you excited??) posted. • I am still working on the gradebook so you can see your grades all together. • Friday will be a Quiz on this week’s work. Maybe last week’s too! • Next week more of the same.
Last Session: • F=Bqv Sin(B,V) • Right hand rule for direction.
A LONG, STRAIGHT WIRE VECTOR! permeability of free space
What is magnetic field at X?? B X 1 Meter 450 1 Ampere Current OUT of Paper DIRECTION? “NW”
REMEMBER:The effect of the sign of a moving Positive and negative charges will feel opposite effects from a magnetic field.
Let’s Look at the effect of crossed E and B Fields: x x x B E x x x v • q , m
x x x B B E E x x x v • q m v = E / B What is the relation between the intensities of the electric and magnetic fields for the particle to move in a straight line ?. FE = q E and FB = q v B If FE = FB the particle will move following a straight line trajectory q E = q v B FB FE •
A charged particle is injected into a Magnetic Field. Can the field do WORK on the particle? A YES B NO C It depends on the direction the particle is moving in with respect to the field. D I want to go back on Spring Break!
The Motion of a Charged Particle in a Magnetic Field The electrical force can do work on a charged particle. Parabola The magnetic force cannot do work on a charged particle.
The Motion of a Charged Particle in a Magnetic Field The magnetic force always remains perpendicular to the velocity and is directed toward the center of the circular path.
21.4 The Mass Spectrometer magnitude of electron charge KE=PE
Smaller Mass Mass Spectrometer
Kratos Profile HV-3 Gas Chromatograph & Direct Probe Mass Spectrometer Description Medium resolution double focusing (E/B) magnetic sector mass spectrometer with gas chromatograph and direct probe inlets; electron impact and chemical ionization sources.
EXAMPLLE: Molecular structure and mass spectrum of 1-acetyl-4-(2-pyridyl)piperazine. The mass spectrum was obtained with a Perkin-Elmer ion trap detector.
An Example A beam of electrons whose kinetic energy is K emerges from a thin-foil “window” at the end of an accelerator tube. There is a metal plate a distance d from this window and perpendicular to the direction of the emerging beam. Show that we can prevent the beam from hitting the plate if we apply a uniform magnetic field B such that
r Problem Continued
