a K passes through a uniform magnetic field . Only the B ext - - PowerPoint PPT Presentation

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a K passes through a uniform magnetic field . Only the B ext - - PowerPoint PPT Presentation

A "ribbon" (width ) with uniform surface current density a K passes through a uniform magnetic field . Only the B ext length along the ribbon is in the field. What is the b magnitude of the force on the ribbon? A. KB B. aKB C.


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SLIDE 1

A "ribbon" (width ) with uniform surface current density passes through a uniform magnetic field . Only the length along the ribbon is in the field. What is the magnitude of the force on the ribbon?

a K Bext b

A. B. C. D. E.

KB aKB abKB bKB/a KB/(ab)

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SLIDE 2

To find the magnetic field at P due to a current-carrying wire we use the Biot-Savart law, In the figure, with shown, which purple vector best represents ?

B B(r) = I ∫ μ0 4π dl × ℜ ̂ ℜ2 dl ℜ

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SLIDE 3

To find the magnetic field at P due to a current-carrying wire we use the Biot-Savart law, What is the direction of the infinitesimal contribution created by current in ?

B B(r) = I ∫ μ0 4π dl × ℜ ̂ ℜ2 B(P) dl

  • A. Up the page
  • B. Directly away from

(in the plane of the page)

  • C. Into the page
  • D. Out of the page
  • E. Some other direction

dl

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SLIDE 4

What is the magnitude of ?

dl × ℜ ̂ ℜ2

A. B. C. D.

  • E. something else!

dl sin θ ℜ2 dl sin θ ℜ3 dl cos θ ℜ2 dl cos θ ℜ3

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SLIDE 5

What is the value of ?

I dl × ℜ ̂ ℜ2

A. B. C. D.

  • E. Other!

I y dx′ [( + x′)2 y2]3/2 ẑ I d x′ x′ [( + x′)2 y2]3/2 ŷ −I d x′ x′ [( + x′)2 y2]3/2 ŷ −I y dx′ [( + x′)2 y2]3/2 ẑ

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SLIDE 6

What do you expect for direction of ? How about direction of generated JUST by the segment of current in red?

B(P) dB(P) dl

A. in plane of page, ditto for , by red B. into page, , by red into page C. into page, , by red out of page D. complicated, ditto for , by red

  • E. Something else!!

B(P) dB(P ) B(P) dB(P ) B(P) dB(P ) B(P) dB(P )