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4 Magnetic Force & Fields.notebook
October 12, 2014
6.3 Magnetic Forces & Fields
Magnetic Field Going Into The Page
Magnetic Field Coming Out of Page
X
X
X
X
X
X
X
X
X
X
X
X
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4 Magnetic Force & Fields.notebook
October 12, 2014
6.3 Magnetic Forces & Fields
The Magnetic Force on a Moving Charge
A particle with a charge q moving with a velocity v through a magnetic field B will experience a magntic force FB with magnitude:
FB = |q|vB sinΘ
Right Hand Rule
v
B
Magnetic force acts on a charge only when the charge is in motion (electric force acts on a charge whether it is moving or not) and the magnetic force is always perpendicular to the magnetic field (electric force is always parallel to electric field). FB
Determines the direction of force on a positve charge moving in a magnetic field.
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4 Magnetic Force & Fields.notebook
October 12, 2014
6.3 Magnetic Forces & Fields
Determine the force acting on each of the charges
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4 Magnetic Force & Fields.notebook
October 12, 2014
6.3 Magnetic Forces & Fields
A charge +q = +6 x 10­6C moves with speed v = 4 x 105 m/s through a magnetic field of strength B = 0.4T, as shown in the figure. What is the magnetic force experienced by q and in what direction is the force?
v
+q
300
B
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4 Magnetic Force & Fields.notebook
October 12, 2014
6.3 Magnetic Forces & Fields
A particle of mass m and charge +q is projected with a velocity v in the plane of the page into a uniform magnetic field B that points into the page. How will the particle move?
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4 Magnetic Force & Fields.notebook
October 12, 2014
6.3 Magnetic Forces & Fields
A particle of mass m and charge +q is projected with a velocity v in the plane of the page into auniform magnetic field B that points into the page. How will the particle move?
B
FB
r
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4 Magnetic Force & Fields.notebook
October 12, 2014
6.3 Magnetic Forces & Fields
A particle of charge ­q is shot into a region that contains an electric field, E, crossed with a perpendicular magnetic field, B. If E = 2 x 104 N/C and B = 0.5 T, what must the speed of the particle if it is to cross this region without being deflected?
X
­q
B
X
X
X
X
X
X
E
X
7
4 Magnetic Force & Fields.notebook
October 12, 2014
6.3 Magnetic Forces & Fields
A particle of charge ­q is shot into a region that contains an electric field, E, crossed with a perpendicular magnetic field, B. If E = 2 x 104 N/C and B = 0.5 T, what must the speed of the particle if it is to cross this region without being deflected?
X
­q
B
X
X
X
X
X
X
FE and FB are in opposite directions so: E
X
8