Electricity II Electric Current Circuit Potential Difference Current
- Slides: 8
Electricity II. Electric Current ª Circuit ª Potential Difference ª Current ª Resistance ª Ohm’s Law
A. Circuit ª Circuit w closed path through which electrons can flow
A. Potential Difference ª Potential Difference (voltage) w difference in electrical potential between two places w large separation of charge creates high voltage w the “push” that causes e- to move from - to + w measured in volts (V)
B. Current ª Current w flow of electrons through a conductor w depends on # of e- passing a point in a given time w measured in amperes (A)
C. Resistance ª Resistance w opposition to the flow of electrons w measured in ohms ( ) Copper - low resistance Tungsten - high resistance
C. Resistance ª Resistance depends on… w the conductor w wire thickness • less resistance in thicker wires w wire length • less resistance in shorter wires w temp - less resistance at low temps
E. Ohm’s Law ª Ohm’s Law V=I×R V: potential difference (V) I: current (A) R: resistance ( ) • Voltage increases when current increases. • Voltage decreases when resistance increases.
E. Ohm’s Law ª A lightbulb with a resistance of 160 is plugged into a 120 -V outlet. What is the current flowing through the bulb? GIVEN: WORK: R = 160 V = 120 V I=? I=V÷R I = (120 V) ÷ (160 ) I = 0. 75 A I V R
