16'360 Lecture 20

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16.360 Lecture 20
Today

• Conductors
• Resistance
• Dielectrics
• Electric boundary conditions
• Capacitance
• Electrostatic potential energy
• Image method

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16.360 Lecture 20
Conductors
Electron drift velocity
Hole drift velocity
Conducting current
Point form of Ohms law
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16.360 Lecture 20
Resistance
General form
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16.360 Lecture 20
Joules law
General form
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16.360 Lecture 20
Dielectrics
Electrical field induced polarization
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16.360 Lecture 20
Dielectrics
P electric polarization field
For homogeneous material
Electric susceptibility
Relative permittivity
Dielectric breakdown
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16.360 Lecture 20
Electric boundary condition
the tangential component is continuous across
the boundary of two media.
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16.360 Lecture 20
Electric boundary condition
the normal component of D changes, the amount of
change is equal to the surface Charge density.
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16.360 Lecture 20
Dielectric-Conductor boundary
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16.360 Lecture 20
Conductor-Conductor boundary
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16.360 Lecture 20
Capacitance
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16.360 Lecture 20
Electrostatic Potential Energy
Image Method
Any given charge above an infinite, perfect
conducting plane is electrically equivalent to
the combination of the give charge and its image
with conducting plane removed.