Phys 115 1st Edition Lecture 7Outline of Last Lecture I. Electric chargeII. Electric forces and Coulomb’s lawIII. Electric fieldsOutline of Current Lecture IV. Work done by electric fieldV. Electric potential energyVI. Electric potentialCurrent Lecture- Textbook reviewo A region has a uniform electric field E pointing to the right (produced by two oppositely-charged plates, not shown) o A positive charge +q is placed in the field and is initially at rest. o The magnitude of the force Feq is proportional to the magnitude of the electric field E and to the magnitude of the charge q: FEq = qE o The force causes the charge to undergo a displacement Δx.o It is useful to describe the change in electric potential energy in a way that does not depend on the size or sign of the charge q.o We therefore define the electric potentialo As for potential energy, only changes in the electric potential ΔV are meaningful and the configuration to which we assign V = 0 is arbitrary. o The units of electric potential are energy/charge = J/Co If we move a charge q through a potential difference ΔV the electric potential energy of the system changes by ΔU = q ΔV.o The most common way of producing a potential difference is to use a battery.o A battery produces an electric potential difference ΔV between its two terminals.o An electric potential difference is also called a voltage and is measured in volts (1volt = 1 V = 1 J/C)o The positive terminal is at a value of the electric potential that is higher than the value at the negative terminalo The potential difference is produced by separation of charge inside the battery.These 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.o If the electric field is uniform (same everywhere), the change in electric potential from the initial to the final position of the charge is o The difference in the electric potential between two locations is the work per unit charge needed to move a charge between the two locations.o The value of the electric potential decreases in the direction in which the electric field points.
View Full Document