Themes > Science > Physics > Electromagnetism > Magnetostatics > Magnetic Field > Force on a moving charge

Given a B-field. Experiment: there exists a (magnetic) force on a moving charge:

\begin{displaymath} F \propto B, v, \sin\theta, q. \end{displaymath}
\begin{figure} \centering \fbox {\begin{picture} (100,90)(0,0) \put(20,20){... ...$} \put(55,10){$\vec{v}$} \put(50,60){$\vec{B}$}\end{picture} } \end{figure}

Summarize everything by introducing a new mathematical operation: vector product

 

% latex2html id marker 4300 \fbox {\begin{minipage} {3in} \begin{equation} \vec{F} = q \vec{v}\times \vec{B}. \end{equation} \end{minipage} }

SI unit: Tesla (T).

Example: $B_{\rm earth} \sim 10^{-4}$T.

If a region of space has both magnetic and electric fields, the net force on a charge is given by the principle of superposition:

\begin{displaymath} \vec{F} = q (\vec{E} + \vec{v}\times \vec{B}). \end{displaymath}

This expression is known as the Lorentz force.


Information provided by: http://www.wpi.edu