Page:Zur Theorie der Strahlung in bewegten Körpern. Berichtigung.djvu/1

 By.

In a paper of same title published a short time ago, I have stated the concept of an apparent mass of cavity radiation, and as its value I have given the quantity

$\frac{8}{3}\frac{h\epsilon_{0}}{c^{2}}$|undefined

where $$h\epsilon_0$$ is the amount of radiation energy contained in the stationary cavity, and $$c$$ is the speed of light. Namely, this value was only valid when quantities of order $$\beta^4$$ were neglected.

Now, was so kind to report to me by letter a new method for the calculation of this mass, yet which gives a different result.

Here, I state the simple method of with his permission, while I am using the notation of my cited paper. The total relative radiation in the cavity is given by

$2\pi i\sin\psi\ d\psi=2\pi i_{0}\frac{c}{c'\cos\alpha}\sin\psi\ d\psi$

The absolute radiation that corresponds to it, is:

Now, according to, the density of the electromagnetic momentum is equal to the absolute radiation divided by $$c^2$$. Thus if we calculate the total