- #1
spaghetti3451
- 1,344
- 33
Homework Statement
Using the tensor transformation law applied to ##F_{\mu\nu}##, show how the electric and magnetic field ##3##-vectors ##\textbf{E}## and ##\textbf{B}## transform under
(a) a rotation about the ##y##-axis,
(b) a boost along the ##z##-axis.
Homework Equations
The Attempt at a Solution
The tensor transformation law applied to ##F_{\mu\nu}## is the following:
##F_{\mu'\nu'}=\frac{\partial x^{\mu}}{\partial x^{\mu'}}\frac{\partial x^{\nu}}{\partial x^{\nu'}}F_{\mu\nu}={{(\Lambda^{-1})}_{\mu'}}^{\mu}{{(\Lambda^{-1})}_{\nu'}}^{\nu}F_{\mu\nu}={\Lambda^{\mu}}_{\mu'}{\Lambda^{\nu}}_{\nu'}F_{\mu\nu}##
(a) A rotation of angle ##\theta## about the ##y##-axis in the counterclockwise sense from the unprimed frame to the primed frame is specified by
##{\Lambda^{\mu'}}_{\mu}=
\left( \begin{array}{cccc}
1 & 0 & 0 & 0 \\
0 & \text{cos}\ \theta & 0 & -\text{sin}\ \theta \\
0 & 0 & 1 & 0 \\
0 & \text{sin}\ \theta & 0 & \text{cos}\ \theta \end{array} \right)
##
Therefore, the same transformation of a rotation of angle ##\theta## about the ##y##-axis in the clockwise sense from the primed frame to the unprimed frame is given by
##{\Lambda^{\mu}}_{\mu'}=
\left( \begin{array}{cccc}
1 & 0 & 0 & 0 \\
0 & \text{cos}\ (-\theta) & 0 & -\text{sin}\ (-\theta) \\
0 & 0 & 1 & 0 \\
0 & \text{sin}\ (-\theta) & 0 & \text{cos}\ (-\theta) \end{array} \right)=
\left( \begin{array}{cccc}
1 & 0 & 0 & 0 \\
0 & \text{cos}\ \theta & 0 & \text{sin}\ \theta \\
0 & 0 & 1 & 0 \\
0 & -\text{sin}\ \theta & 0 & \text{cos}\ \theta \end{array} \right)
##
Have I made a mistake?