PS 301

Circuits

Electric Potential (voltage)

E-field vs M-field

+ & - charges N- & S- poles

Circuits—Voltage Sources

Electric potential difference (continued)Example: water from a higher reservoir to a lower one—flow

continues until no difference

– no flow of charge occurs when potential difference is zero

Resistance

Electric potential difference (continued)• Water and electric circuits compared

Electric Circuits

Devices connect to a circuit in one of two ways:

• Series • Parallel

Circuits in Series

Circuits in Parallel

Series

Today ::: Ohm’s LawOhm’s Law

relationship between current, voltage, and resistance

Current in a circuit varies in direct proportion to the potential difference (voltage) and inversely with the resistance:

I

V R

R, for Solving

resistance

voltage current

V

I

Slope = V = R

I

Today

Measurements of voltage, current and resistance

Front desk

1

Computer

Computer

22

Computer

Computer

3

Computer

Computer

44

Computer

Computer

5 6 7 8