Textbook: 7.4 Homework: pg. 358 – 359 #1 – 8 Electric Potential Textbook: 7.4 Homework: pg. 358 – 359 #1 – 8

Electric Potential Energy Work done is the change in the electric potential energy of the charge in an electric field. The electric potential energy stored in a system with two charges q1 and q2, separated by a distance r is: Ex. Calculate the electric potential energy stored in a hydrogen atom: - q = 1.60 x 10-19 C - r = 5.29 x 10-11 m q1q2 < 0 charges are bound q1q2 > 0 charges are unbound

Electric Potential Electric potential energy per unit charge is referred to as electric potential or just potential. The electric potential (V) a distance r away from a charge q is: The change in electric potential between two points is the electric potential difference V (also know as the voltage)

Important Relationships In general For a parallel plate (electric field,  = constant) Pg. 354 #1 - 4

Draw two equal positive point charges and connect them with a line. (a) Is there a point on the line at which the electric field is zero? (b) Is there a point on the line at which the electric potential is zero? (c) Explain the difference between the two answers.

A positive test charge of 1 A positive test charge of 1.5 x 10-6 C is placed in an electric field 10 cm from another charge of magnitude - 5.0 x 10-6 C that is anchored in place. a) What is the electric potential energy of the test charge? [-6.8 x 10-1 J] b) What is the potential difference between the test charge’s initial position and a point 5.0 cm closer to the negative charge? [-4.5 x 105 V]