# Shared Flashcard Set

## Details

Tipler Physics Ch 26
Magnetic Field
18
Physics
05/26/2008

Term
 Force on a moving charged particle
Definition
 F = qv x B = qvBsinΘ, where theta is the angle between the velocity V and field B
Term
 What are the units of a tesla?
Definition
 1 T = 1 N/(C m/s) = 1 N/(A m)
Term
 What is a Gauss?
Definition
 1 G = 10-4 T
Term
 If the velocity vector of a positive charge is in the +x direction, and the B field is in the -Y direction, which direction is F?
Definition
 -Z direction, according to the right hand rule
Term
 If the velocity vector of a negative charge is in the +x direction, and the B field is in the -Y direction, which direction is F?
Definition
 + Z.  The RHR dictates that the force will be in the -Z direction, but because the charge is negative, F=qV x Bthe force is in the negative direction of the RHR
Term
 What is the magnetic force on a straight segment of current-carrying wire?
Definition
 F = IL x B
Term
 What is the magnetic force on a current element?
Definition
 dF = I dl x B
Term
 What is a cyclotron period?
Definition
 T = 2 pi m/(qB)
Term
 What is a cyclotron frequency?
Definition
 f = 1/T = qB/(2 pi m)
Term
 What is the velocity selector?
Definition
 v = E/B It is set up as two capacitor plates with a constant electric field between them.  The E field is perpendicular to a B field.  If a particle is moving at a certain velocity, the E field will balance out the B field that is created by the particle.  Only a charge of that velocity can move through the capacitors undeflected
Term
 What is the magnitude of torque on a rectangular current loop?
Definition
 τ = NIABsinΘWhere N = the number of loopsI=currentA = area enclosed by loopB = B fieldsinΘ =  angle between B field and the orientation of the loop 'n' (found by RHR, fingers curl around direction of I, thumb points to n)
Term
 What is the magnetic dipole moment of a current loop?
Definition
 μ = NIAnN = number of loopsI = currentA = arean = see card 11
Term
 What is the torque on a current loop?
Definition
 τ = μ x BAll vector units
Term
 What is the potential energy of a magnetic dipole?
Definition
 U = -μBcosΘ
Term
 What is the Hall effect?
Definition
 When charges are traveling in a conducting wire in a B field perpendicular to their velocity, charges will be pushed to one side because of the force the B field exerts on them.  The separation of charge is the Hall effect
Term
 What is the Hall voltage?
Definition
 VH = EH ω = vd Bωω = width of the strip that the potential difference is being measured.  Vd = drift velocity of electrons in a wireEH = the electric field created by the separation of charges
Term
 Why is there a Hall voltage?
Definition
 A Hall voltage exists because when a magnetic field pushes like charges to one end of a wire or strip, there is a difference in voltage between the top of the wire, which holds one type of charge, and the bottom of the wire, which holds the opposite charge.  This difference in charge can be measured
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