1 / 4

Physics 17: Electric Potential & Electric Energy

Physics 17: Electric Potential & Electric Energy. Christopher Chui. Electric Potential & Potential Difference. Electric potential = potential energy/charge =PE/q Potential difference, V ab = V a – V b = - W ba /q

ramona-smith
Télécharger la présentation

Physics 17: Electric Potential & Electric Energy

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. Physics 17: Electric Potential & Electric Energy Christopher Chui Physics 17: Electric Potential & Electric Energy - Christopher Chui

  2. Electric Potential & Potential Difference • Electric potential = potential energy/charge =PE/q • Potential difference, Vab = Va – Vb = - Wba/q • = negative work done by the electric force to move the charge from point b  point a • 1 V = 1J/C in honor of Volta (1745-1827) = p.d. • The ground is chosen to have 0 V • Change in PE of a charge q between a and b=q Vba • Typical voltages: Thundercloud 108V, HV Pwrline106V,TV tube 104V,nerve 10-1 V,EKG 10–4 V • W = Fd = qEd=qVba Vba = Ed • An equipotential surface is perpendicular to E • Conductors are equipotential surfaces Physics 17: Electric Potential & Electric Energy - Christopher Chui

  3. Electric Potential due a Point Charge • Electric potential of point charge (V=0 at infinity) = kQ/r, where k = 1/4peo = 9 x 109 N.m2/C2 • Potentials add as scalars, but fields add as vectors • Two equal point charges Q, of opposite sign, separated by a distance l, are called an electric dipole • V = kQl cos q / r2 for dipole with r >> l • Dipole moment p = Q l  V = kp cos q / r2 • Capacitance is a device that can store electric charge • For a given capacitor, the amount of charge Q acquired is proportional to the potential difference V • Q = CV where C in the capacitance in Farad, 1F=1C/V • C= eo A/d for //plate capacitor Physics 17: Electric Potential & Electric Energy - Christopher Chui

  4. Dielectrics and Storage of E Energy • C = Keo A/d where K is dielectric constant for //plate • C = e A/d where e = Keo = permittivity of the material • Energy stored in cap U = ½ QV = ½ CV2 = ½ Q2/C • Energy stored / unit volume in E field = ½ eoE2 • CRT (cathode ray tube) is used in TV, computer monitors, and oscilloscopes • ECG is a record of the potential changes of a person’s heart. The amount of charge depends on the size of the cell, but is approximately 10-3 C/m2 of surface. For a cell with surface area 10-5 m2, the total charge on either side ~ 10-8 C Physics 17: Electric Potential & Electric Energy - Christopher Chui

More Related