| Work done by a conservative force (Coulomb's force) | Negative of the change in a potential energy. |
| ΔPE = - Wab= - qEx (xf – xi) | Only for a uniform field (Ex) for a particle that undergoes a displacement along a given axis. |
| SI unit of energy | Jouls (J) |
| The electric potential difference: | ΔV = VB – VA = ΔPE / q |
| The electric potential difference in a uniform electric field: | ΔV = -Ex (xf – xi) |
| Electric potential is: | Characteristically of the field only.
Independent of any testing charge. |
| Electric potential energy is: | Characteristically of the charge-field system.
Dependent on a test charge. |
| Explain the relation between Electric Potential and Charge Movements: | When Vo=0m/s, + charges accelerate from regions of high potential to low potential, - charges will accelerate from low potential to high potential, and work must be done on - charges to make them go in the opposite direction. |
| The potential created by a point charge q at any distance r from the charge is: | V=ke(q/r) |
| Difference between the electric field and electric potential. | The electric field is proportional to 1/r^2
The electric potential is proportional to 1/r |
| The potential energy for a 2-particle system | The work required to bring q2 from infinity to P without acceleration.
PE = q2V1= ke((q1*q2)/r) |
| What happens to PE and Wo when the charges have the same sign? | PE is + and Wo is + when force the 2 charges to get nearer one another. |
| What happens to PE and Wo when the charges have the dif. sign? | PE is - and Wo is + when force the 2 charges to get far from one another. |
| Problem-Solving w/ Electric Potential (Point Charges) | - Draw a diagram of all charges.
- Note the point of interest P.
- Calculate the r from each charge to P.
- Use V = keq/r
- V is + if +q and - if the charge is -q. |
| What are the caracteristics of a charged conductor in electrostatic eq.? | All points on the surface W = 0, VA = VB.
E = 0 inside the conductor.
The E is outside the conductor, and is perpendicular to the surface. |
| The e- Volt | The kinetic energy that an e-/p+ gains when accelerated through 1 V. |
| Equipotential surface | The surface on which all points are at the same potential. W = 0, VA = VB. And the E outside the surface is perpendicular to the surface. |
