Download presentation
Presentation is loading. Please wait.
Published byJeremy Adams Modified over 9 years ago
1
General Physics 2Electric Potential1 As with mechanics, energy is a useful quantity in studying electric forces electric potential or potential electric potential energy per unit charge potential difference, Φ only difference in potential energy is meaningful V e is the electrostatic potential energy relative to some reference point Volt: 1 V = 1 J/C
2
General Physics 2Electric Potential2 Analogy to Gravitational PE ΦbΦb ΦaΦa Φ ab Electric potential energy depends on charge Gravitation PE depends on mass
3
General Physics 2Electric Potential3 Electric Potential of Point Charge Set V=0 at a distance of infinity
4
General Physics 2Electric Potential4 Electric Potential of Multiple Charged Objects Superposition principle
5
General Physics 2Electric Potential5
6
General Physics 2Electric Potential6 Equipotential Lines connect points in space at same potential equipotential surface is perpendicular to electric field lines
7
General Physics 2Electric Potential7 Electric Field & Equipotential Lines Draw field lines and equipotential lines for the following charge distributions -
8
General Physics 2Electric Potential8 Electric Field & Equipotential Lines Draw field lines and equipotential lines for the following charge distributions +
9
General Physics 2Electric Potential9 Relating Electric Field to Potential The change in electrical potential for a small displacement in a static electric field
10
General Physics 2Electric Potential10 Electrostatic Potential & PE When dealing with discrete point charges: V e and Φ are scalarsF and E are vectors
11
Electric Potential + charges move from high to low potential Think of analogy with gravitational PE, where object with positive PE will fall if released. Here, p+ has high PE when near + plate and will “fall” toward negative plate when released Think of + charge when wondering if something is high or low potential
12
Electric Potential - charges move from low to high potential Unlike mass, charge can be + or -. Thus, PE depends on the sign of the charge. For example, an e- will have high PE when near the - plate and will “fall” toward the + plate when released -- High PElow PE
13
General Physics 2Capacitors13 Capacitance a capacitor stores electric charge
14
General Physics 2Capacitors14 Properties of Capacitors Capacitance, C Q = C V Farad (F) = Coulomb / Volt C depends on size, shape, relative position of parallel plates (and material that separates them) permittivity of free space = 8.85 x 10 -12 C 2 /(N m 2) surface area per plate separation between plates
16
General Physics 2Electric Potential16 Electron Volt, a Unit of Energy electron volt (eV) Joule is very large for dealing w/electrons, atoms and molecules eV is energy required to move 1 e- through a potential difference of 1V 1 eV = q e V = (1.6 x 10 -19 C)(1.0 V) 1 eV = 1.6 x 10 -19 J
17
General Physics 2Electric Potential17 Sign of Electric PE PE = 0 at infinity Did you have to do work to bring charges from infinity? yes -> charges have positive PE Example: no -> charges have negative PE Example: -- -+
18
ConcepTest 1. positive 2. negative 3. zero
19
ConcepTest
20
General Physics 2Electric Potential20 Plug & Chug How much work does the electric field do in moving a -7.7 C charge from the ground to a point whose potential is +55 V higher?
21
General Physics 2Electric Potential21 Think-Pair-Share How much kinetic energy will an electron gain (in joules and eV) if it accelerates through a potential difference of 23,000 V in a TV picture tube? What is its final velocity?
22
General Physics 2Electric Potential22 Electric Potential & Electric Field For a uniform electric field uniform electric field
23
General Physics 2Electric Potential23 Electric Field & Equipotential Lines Draw field lines and equipotential lines for the following charge distributions --
24
Which set has a positive potential energy?
25
Which set has a negative potential energy?
26
General Physics 2Electric Potential26 Plug & Chug What is the electric potential 15.0 cm from a 4.00 x 10 -6 C point charge?
27
General Physics 2Electric Potential27 Think-Pair-Share What is the potential at point A, taking V=0 at a great distance?
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.