288' Magnetic Force on a CurrentCarrying Wire

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28-8. Magnetic Force on a Current-Carrying Wire
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28-8. Magnetic Force on a Current-Carrying Wire
10 g wire of length 20 cm in a B-field 0.5 T. To
remove the tension, (i) what direction is the
current? (ii) what is the magnitude of the
current?
B force upward Current to the right
mg i L B (0.01) (9.8) i (0.2) (0.5)
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28-9. Torque on a Current Loop
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28-10. Magnetic Dipole Moment
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28-10. Magnetic Dipole Moment
Inner loop Radius 4 cm, Current 3A,
clockwise Outer loop Radius 6 cm, Current 7A,
clockwise (i) what is the direction of the net
B-dipole moment? (ii) what is its magnitude?
Currents both clockwise gtgt dipole moment into
the page
m (1) (3) (p 0.042) (1) (7) (p 0.062)
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28-10. Magnetic Dipole Moment
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28-10. Magnetic Dipole Moment
(i) Rank the orientations according to the
magnitude of the torque (ii) Rank the
orientations according to the potential energy
1 2 3 4
1 4 gt 2 3
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29-2. B-Field Due to a Current
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29-2. B-Field Due to a Current
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29-2. B-Field Due to a Current
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29-2. B-Field Due to a Current
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29-2. B-Field Due to a Current
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29-2. B-Field Due to a Current
Long parallel wires same current Rank according
to the magnitude of the net B-field at the center

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29-2. B-Field Due to a Current
B-field at P is zero. Current 2 is (a) into or
(b) out of the page? Current 2 is (a) bigger
or (b) smaller than the current 1?
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29-2. B-Field Due to a Current
B-field at P direction?
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29-2. B-Field Due to a Current
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29-2. B-Field Due to a Current
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29-2. B-Field Due to a Current
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29-2. B-Field Due to a Current
Same current (clockwise) Which has the largest
magnitude of the B-field at the center ?
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29-2. B-Field Due to a Current
R1 10 cm, R2 6 cm Current 0.3 A What is the
magnitude of the net B-field at the center ?
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29-3. Force between Two Parallel Currents
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29-3. Force between Two Parallel Currents
Same current (into or out of the plane) Rank
the wires according to the magnitude on each due
to the other two.
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29-4. Amperes Law
Line integral of B-field
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29-4. Amperes Law
Sign of the current?
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29-4. Amperes Law
Same current (parallel or antiparallel) Rank
the loops according to the magnitude of the
integral
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29-4. Amperes Law
What is the magnitude of the integral ?
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29-4. Amperes Law
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29-4. Amperes Law
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29-5. Solenoids
Solenoid
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29-5. Solenoids

• No B-Field outside
• Uniform Inside

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29-6. Current-Carrying Coil as a Magnetic Dipole
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29-6. Current-Carrying Coil as a Magnetic Dipole
Loops same currents, radius r or 2r Rank
according to the magnitude of the B-field at the
mid-point
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