| A | B | 
| repulsive force | two charges of like sign | 
| attractive force | two charges of unlike signs | 
| neutral object | equal amounts of positive & negative charges | 
| electric force between objects | can be either attraction or repulsion | 
| electric field lines around a negative charge | always point inward | 
| unit potential difference is measured in | volts | 
| batteries | have a positive & negative terminal | 
| current (I) | rate at which charges move thru a conductor | 
| brightness of a bulb is due to | resistance in the filament | 
| SI unit for resistance | ohm | 
| how easily charges move | depends on how tightly electrons are held | 
| letter to represent current | I | 
| letter to represent voltage | V | 
| letter to represent resistance | R | 
| letter to represent power | P | 
| insulator | has high resistance | 
| conductor | has low resistance | 
| super conductor | has the least resistance | 
| semiconductor | has less resistance than an insulator and more than a conductor | 
| circuit breaker | a device to protect a circuit from overload |