electric potential 1

# electric potential 1 - Alessandro Volta(1745-1827 Last Time...

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1 1 The Electric Potential Alessandro Volta (1745-1827) This lecture: HRW 24.1-24.8 For next time: HRW 24.9-24.12 2 Last Time E=0 in a conductor, and E is to conducting surfaces Gauss’ Law can be used to determine E when E is constant and perpendicular to a Gaussian surface (imaginary). Today The Electric Potential Equipotential surfaces The electric potential of point charges 3 Potential Energy (review) Potential energy , U (r ) , describes a conservative force. The reference point , where U=0, is chosen for convenience. For conservative forces, K+U=E, a constant. kinetic energy total energy x U •Work ± is ±path± independent . • In a round trip, U is unchanged (conserved). i f r r dW =F•ds i f U=U -U=-W Change in potential energy Work by the field Δ r r f x i dU F=- ; U=-F•ds dx 1 2 4 Electric Potential Energy Interactive Lecture Question #7.1 What is the change in potential energy of a 3 C charge in a uniform electric field of 10 N/C when it is moved along the path shown? 5 m initial final =− ∫∫ r r U=- dW=- F•ds Eq x The potential energy gets lower (the charge would move to the right on its own). x y x U The reference point for U is arbitrary here N =-10 3C 5m =-150N m =-150 J C

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2 5 Electric Potential Units: Electric potential is measured in Volts (V). 1 J of work moves a 1 C charge across a 1 V potential difference. 1 V = 1 J/C The electric potential , V( r ) , is typically used instead of the electric potential energy , U( r ).
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electric potential 1 - Alessandro Volta(1745-1827 Last Time...

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