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Agenda. Today Problems in Last Few Chapters Tomorrow Quiz on 21-23, Lab Wed Shand begins 25. Charge Distribution: Conducting Donut. Point Charge Outside on Left Which is correct? Why?. How to Solve this Problem Practice Ch. 22. What is Electric Field Produced by This? Sphere
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Agenda • Today • Problems in Last Few Chapters • Tomorrow • Quiz on 21-23, Lab • Wed • Shand begins 25
Charge Distribution: Conducting Donut Point Charge Outside on Left Which is correct? Why?
How to Solve this ProblemPractice Ch. 22 What is Electric Field Produced by This? Sphere Hole in Sphere Constant charge density R2 R1 Hole Located at x=-R1/2 R2 = R1/8 Charge Density = r
How to Create a hole? Simpler way to look at this? R2 R1 Hole Located at x=-R1/2 R2 = R1/8 Charge Density = r
R2 R1 How to Create a hole? Simpler way to look at this? Hole Located at x=-R1/2 R2 = R1/8 Charge Density = r
How to Create a hole? Make two spheres One +r & one –r Superposition [Add together] r = - r = + R2 R1 Hole Located at x=-R1/2 R2 = R1/8 Charge Density = r Try This?
Electric Field & Potential Two Metal Spheres Concentric Outer Hollow Iner: Charged +Q Outer: Charged -Q R3 R2 R1
Electric Field & PotentialEverywhere? Two Metal Spheres Concentric Outer Hollow Iner: Charged +Q Outer: Charged -Q R3 R2 R1 Specific Regions 0 <r <R1 R1 < r < R2 R2 < r < R3 R3 < r < Infinity
Electric Field & Potential Two Metal Spheres Concentric Outer Hollow Iner: Charged +Q Outer: Charged -Q R3 R2 R1 Specific Regions 0 <r <R1 R1 < r < R2 R2 < r < R3 R3 < r < Infinity
Electric Field & Potential -Q Where is charge located? R3 R2 R1 +Q Specific Regions 0 <r <R1 R1 < r < R2 R2 < r < R3 R3 < r < Infinity
Metals: E = 0 Inside Metal -Q Where is charge located? - - R3 - - - - R2 - + + - - - + + - +Q + R1 - Specific Regions 0 <r <R1 R1 < r < R2 R2 < r < R3 R3 < r < Infinity - + - + - - - - - - - -
Metals: E = 0 Inside Metal -Q Gauss’s Law Field =0 if QENCL=0 Charges on Outer Surface - - R3 - - - - R2 - + + - - - + + - +Q + R1 - Specific Regions 0 <r <R1 R1 < r < R2 R2 < r < R3 R3 < r < Infinity - + - + - - - - - - - -
Electric Field? Specific Regions 0 <r <R1: E = ? R1 < r < R2: E=? R2 < r < R3: E = ? R3 < r < Infinity: E = ? -Q - - R3 - - - - R2 - + + - - - + + - +Q + R1 - - + - + - - - - - - - -
Electric Field? Specific Regions 0 <r <R1: E = 0 R1 < r < R2: E=? R2 < r < R3: E = 0 R3 < r < Infinity: E = 0 -Q - - R3 - - - - R2 - + + - - - + + - +Q + R1 - - + - + - - - - - - - -
Electric Field? Specific Regions 0 <r <R1: E = 0 R1 < r < R2: E = kQ/r2 R2 < r < R3: E = 0 R3 < r < Infinity: E = 0 -Q - - R3 - - - - R2 - + + - - - + + - +Q + R1 - - + - + - - - - - - - -
Potential First: Reference Point -Q Gauss’s Law Field =0 if QENCL=0 Charges on Outer Surface - - R3 - - - - R2 - + + - - - + + - +Q + R1 - Specific Regions 0 <r <R1 R1 < r < R2 R2 < r < R3 R3 < r < Infinity - + - + - - - - - - - -
Potential: Reference Point -Q V at infinity = 0 (3D ref) E in metal = 0 E outside: kQENCL/r2 - - R3 - - - - R2 - + + - - - + + - +Q + R1 - Specific Regions 0 <r <R1 R1 < r < R2 R2 < r < R3 R3 < r < Infinity - + - + - - - - - - - -
Potential: Reference PointStart at r=infinity, work way in -Q V at infinity = 0 (3D ref) E in metal = 0 E outside: kQENCL/r2 - - R3 - - - - R2 - + + - - - + + - +Q + R1 - Specific Regions 0 <r <R1 R1 < r < R2 R2 < r < R3 R3 < r < Infinity - + - + - - - - - - - -
Where is V =0?Where is V= Constant?Try this? Capacitance? (C=Q/V) -Q V at infinity = 0 (3D ref) E in metal = 0 E outside: kQENCL/r2 - - R3 - - - - R2 - + + - - - + + - +Q + R1 - Specific Regions 0 <r <R1 R1 < r < R2 R2 < r < R3 R3 < r < Infinity - + - + - - - - - - - -
Agenda • Today • Problems in Last Few Chapters • Tomorrow • Quiz on 21-23, Lab • Wed • Shand begins 25