1 / 12

Advanced Higher Physics

Advanced Higher Physics. Electric Potential. Electric Potential 1. V = work done / q (measured in J C -1 ) Defined as ‘the work done per unit positive charge in moving a charge from infinity to a point in an electrical field’ Gives the definition of the volt -

renata
Télécharger la présentation

Advanced Higher Physics

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. Advanced Higher Physics Electric Potential

  2. Electric Potential 1 • V = work done / q (measured in J C-1) • Defined as ‘the work done per unit positive charge in moving a charge from infinity to a point in an electrical field’ • Gives the definition of the volt - one volt (1 V) = one joule per coulomb (1 JC-1)

  3. d A B Electric Potential 2 • The potential difference (p.d.) between two points A and B is the work done per unit charge in moving between points A and B. ( also, * This is only true for a UNIFORM field. )

  4. Law of conservation of energy tells us that work done in moving charge from point A to point B is independent of the route taken. If the p.d. between A and B is V, the same amount of work must be done in moving a unit of charge from A to B, whatever path is taken. This is because the electric field is a conservative field. Electric Potential 3

  5. Electric Potential 4 • From the equation E = V / d we can see that electrical field strength, E, can be expressed volts per metre, V m-1 • E can be thought of as a ‘potential gradient’ • In a non-uniform field,

  6. Electric Potential 5 • using r to represent distance, • But, we already know that - • Combining these gives -

  7. Electric Potential 6 • Integrating as shown, we get

  8. Electric Potential 7 • NB - be careful with the sign of the potential. • In moving a positive charge from infinity to r, the charge will have gained potential energy, as work has to be done on the charge against the electric field.

  9. Electric Potential 8 • So if we have defined the potential to be zero at infinity, the potential V must be positive for all r less than infinity. Thus the potential at r is given by -

  10. Electric Potential 9 • Unlike the electric field, the electric potential around a point charge decays as 1 / r , not 1 / r2. • The potential is a scalar quantity, not a vector quantity, although its sign is determined by the sign of the charge Q.

  11. Electric Potential 10 • The field strength and potential around a positive point charge are plotted below

  12. We can plot the equipotential lines (connecting points of the same potential) around a point charge, as shown below The equipotentials form a set of concentric spheres around the charge Note that the equipotentials cut the electric field lines at right angles. There is no work done in moving a charged particle along an equipotential. Electric Potential 11

More Related