1 / 6

Focus on Electric Potential

Focus on Electric Potential. AP Physics B Kernion. Main Points. Electrical Potential Energy (U E ), scalar quantity depends on: position in the E-field amount of charge magnitude of the E-field at that point For uniform E-fields: ΔU = - qEd for a positive charge moving ALONG the field

alodie
Télécharger la présentation

Focus on Electric Potential

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. Focus on Electric Potential AP Physics B Kernion

  2. Main Points • Electrical Potential Energy (UE), scalar quantity depends on: • position in the E-field • amount of charge • magnitude of the E-field at that point • For uniform E-fields: • ΔU = -qEd for a positive charge moving ALONG the field • ΔU = qEdfor a negative charge moving ALONG the field • A new scalar quantity, Electric potential (V) is defined as the electric potential energy per unit charge • U/q = V (You MUST use the sign on q) • ΔU/q = ΔV (The change in electric potential...voltage) • unit = J/C = volt (v)

  3. For movement along a uniform E-field • For a positive charge • ΔU/q = ΔV = -qEd/q = -Ed • For a negative charge • ΔU/q = ΔV = qEd/-q = -Ed • Movement ALONG the field ALWAYS lowers the electrical potential • N/C = V/m

  4. Example • A proton is released from rest in a uniform E-field (E = 8 x 104 V/m) directed to the right. The proton moves a distance of 0.5 m along the field. Find the following quantities • ΔV, ΔU,ΔK, v, WE • ΔV = -Ed = (8x104)(0.5) = 4x104 volts • ΔU = qΔV = 1.6x10-19C (4x104v) = 6.4x10-15J • ΔK = -ΔU = -6.4x10-15 J = ½ mv2 = ½(1.67x10-27kg) • v = 2.8x106m/s • WE = -ΔU = ΔK = -6.4x10-15 J

  5. Electric Potential and non-uniform E-fields + Electric potential caused by a point particle V = kq/r (keep sign on charge)

  6. Example Problem Find the electric potential at point p p 4 m 3 m q1 q2 (0.5 μC) (-2.0 μC) VP = ∑kq/r = k[q1/r1 + q2/r2] VP = 9x109[(0.5x10-6/4) + (-2x10-6/5) VP = -2475 volts

More Related