PHY 182 1st Edition Lecture 19Outline of Last Lecture I. How to Calculate Electric PotentialII. Deriving an Expression for Electric PotentialOutline of Current Lecture I. How to Calculate Potential DifferenceII. Corona DischargeIII. Equipotential SurfacesCurrent LectureHow to Calculate Potential Difference- If you already know the magnitude of the electric field, there is sometimes an easier approach for finding potential difference.- You can take the integral of the dot product of the electric field and the displacement. (Note that you must include a negative sign in front of the integral.)- If the movement is in the same direction as the electric field, the electric potential is decreasing. Thus, the sign of the potential difference should be negative.- 1 eV is defined as the energy of an electron moving through a potential difference of 1 volt.- You can use this integrating method for a point charge and integrate with respect to the radial distance from the charge. The integral will yield the same value for potential difference that we previously derived.Corona DischargeThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Air is normally a good insulator of charge. This is why you can put your hand near a charged object and usually not feel anything unless you are in direct contact with theobject.- However, at an electric field magnitude of approximately 3 million V/m, air becomes a conductor of charge. This occurs because of ionization.- To find the maximum potential of a sphere, multiply the radius of the sphere by 3 million.Equipotential Surfaces- Equipotential surfaces are essentially analogous to a topographical map, except they show electric potential instead of altitude.- The electric field lines are always perpendicular to the equipotential surface.- Remember that these are 3-D surfaces.- All points on an equipotential surface have the same electric potential.- For a charged conductor, its surface is an equipotential surface because the charge allspreads out to the surface. Thus, the surface of the object has the same potential at all
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