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Electric Potential Difference Or Voltage. Forces and Fields 8. 3.00m. 1.0kg. 2.00m. Consider a mass positioned in a gravitational field. A mass above a reference level (ground) possesses gravitational potential energy.
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Electric Potential DifferenceOr Voltage Forces and Fields 8
3.00m 1.0kg 2.00m Consider a mass positioned in a gravitational field • A mass above a reference level (ground) possesses gravitational potential energy. • Work must be done against the force of gravity to increase Ep. (Lifting the object further off the ground increases Ep) • Between the two points in the gravitational field above the ground,(2m and 5m) the difference in Ep can be determined.
- - d d - - + charge - charge Electric Potential Energy • Consider a charge placed within an electric field • moving the – charge away from the positive charge requires work which increases electric potential energy and moving the – charge toward the negative charge also does the same
+ - + - d d Electrical Ep changes when work is done in moving a charge from one point to another within an electric field • To increase Ep between two unlike charges, move them farther apart. Ep lesser Ep greater -q1 + + d Low Ep Higher Ep
d d + + + + To increase electric Ep between two like charges, move them closer together • the ratio of the change in energy (work, potential or kinetic) per unit charge (1.00 C) within an electrical field Low Ep Higher Ep Electrical Potential Difference or Voltage (V)
+ + ++ + + + + - - - - - - - - + + Eg) two oppositely charged plates • Between the two points that a positive charge has moved within the electric field, there exists a voltage uniform High Ep low Ep
Electric potential difference or voltage is the change in potential energy per unit charge. • The ratio of E/q is called a volt and is named after Alex Volta who invented the battery Equation: In Joules In Coulombs
Examples: • A 12.0 volt battery supplies 12.0 joules of energy to move a 1.00 C charge through a circuit. • The voltage of 1.00 V between two points in an electric field means that 1.00 J of energy is needed to move a 1.00 C charge between the two points in the field.
+ + ++ + + + + - - - - - - - - 1.00 V - -
+ + ++ + + + + - - - - - - - - Example: • A charge of -2.60 X 10-3uC is moved from a positive plate to a negative plate by doing 1.17 X 10-5 J of work. What is the potential difference between the plates? - -
2nd Equation for Voltage • The potential difference or voltage between two oppositely charged plates is determined by the magnitude of the uniform electric field, E, and the distance between the plates. • Equation for voltage between oppositely charged plates: Work, Ep or Ek, energy
+ + ++ + + + + - - - - - - - - Example: • Determine the electric field strength between 2 oppositely charged plates 25 cm apart to which 120 V is supplied. 0.25 m V = 120 v