Physics 121: Electricity & Magnetism – Lecture 9

Carsten Denker

NJIT Physics DepartmentCenter for Solar–Terrestrial

Research

March 21, 2007 Center for Solar-Terrestrial Research

Magnetic FieldsThe force acting on a charged particle moving with velocity through a magnetic field is always perpendicular to and .Opposite magnetic poles attract each other, and like magnetic poles repel each other.

BF

v

v

BB

sinBF q v B

BF qv B

March 21, 2007 Center for Solar-Terrestrial Research

Crossed Fields

Discovery of the electron: cathode ray tube

Hall effect

Both an electric field and a magnetic field can produce a force on a charged particle.

E

B

March 21, 2007 Center for Solar-Terrestrial Research

A Circulating Charged Particle

2mvqvB

r

March 21, 2007 Center for Solar-Terrestrial Research

Magnetic Force on a Current–Carrying Wire

BF iL B

March 21, 2007 Center for Solar-Terrestrial Research

Torque on a Current Loop