Electrical Power and Resistors
Home Electrostatics Coulomb's Law Electric Field Gauss's Law Electric Potential Energy Electric Potential Capacitors Energy in Capacitors Current Electrical Power and Resistors Kirchhoff's Rules RC Circuits Magnetic Fields Moving Charges in a B-Field Magnetic Field of a Moving Charge Magnetic Field Due to a Current Ampere's Law

 

Procedures
Lectures
Quizzes
Exams
Assignments
MidTerm
Final

Phys 4, Section 2                                                                 Feb 6, 2002

 

Power dissipation

Current flow through a resistor causes heating (called Joule heating or resistive heating).  This represents a loss of energy from the system

Power is rate of doing work, so for electrical quantities,

dW = Vdq

P = dW/dt =Vdq/dt = VI = I2R = V2/R

Resistor Combinations

Parallel:    1/Reff = 1/R1 + 1/R2 + ...

Series:    Reff = R1 + R2 + ...

Effective resistance of resistors in series is always more than the largest resistor in the set, while the effective resistance of resistors in parallel is always less than the smallest resistor in the set.