1 / 21

9: Motion in Fields

9: Motion in Fields. 9.3 Electrical field, potential and energy. Electric Fields Recap: Coulomb’s law : Electric field strength:. F = kQq r 2. …the force per unit charge experienced by a small positive point charge placed in the field. E = kQ r 2. Electrical Potential

galia
Download Presentation

9: Motion in Fields

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 9: Motion in Fields 9.3 Electrical field, potential and energy

  2. Electric Fields Recap: Coulomb’s law: Electric field strength: F = kQq r2 …the force per unit charge experienced by a small positive point charge placed in the field. E = kQ r2

  3. Electrical Potential It can be shown that... or... Where... V = Electrical potential (Volts or JC-1) r = distance from centre of point charge (m) Q = point charge (Coulombs) k = Coulomb constant = 8.99 x 109 Nm2 C−2 The electrical potential at a point in a field is defined as the work done per unit charge in bringing a positive test charge from infinity to the point in the field. V = kQ r V = 1Q 4πε0 r

  4. E.g. Calculate the potential due to the proton in a hydrogen atom at a distance 0.5 x 10-10m. ( k = 8.99  109 N m2 C-2 ) A: V= 29V

  5. Electric Potential Energy Again it can be shown that... or... The electrical potential energy of a point charge at any point is defined as the work done in moving the charge from infinity to that point. Ep = kQq r Ep = 1Qq 4πε0 r E.g. Calculate the potential energy between the proton in a hydrogen atom and an electron orbiting at radius 0.5 x 10-10m. ( k = 8.99  109 N m2 C-2 ) A: E = -46 x 10-19J

  6. Work done moving a charge If a charge is moved from one point (x) to another (y), where the potential is different, work is done. Work done = Final Ep – Initial Ep = Vyq - Vxq The path taken does not affect the work done. Work done will equal the change in potential energy. x y

  7. Equipotentials Equipotential surfaces also exist in electric fields...

  8. Subtitle Text

  9. Potential gradient Again, this will be equal to the field strength at a point in an electrical field... Work done to move a charge from one potential to another = qΔV But also W = FΔx So... FΔx = qΔV So... E = (-) ΔV Δx

  10. Subtitle Text

  11. Subtitle Text

  12. Subtitle Text

  13. Subtitle Text

  14. Subtitle Text

  15. Subtitle Text

  16. Subtitle Text

  17. Subtitle Text

  18. Subtitle Text

  19. Subtitle Text

  20. Subtitle Text

  21. Subtitle Text

More Related