Consider the two identical rods in Figure 27.26, one moving and the other at rest relative to observer E, at rest in the Earth reference frame. Suppose a second observer \(\mathrm{M}\) moves along with the moving rod.

(a) Which rod has the greater charge density according to observer M?

(b) Suppose the charge on the rod moving in the Earth reference frame is adjusted so that its charge density as seen by observer E is the same as the charge density of the rod at rest in the Earth reference frame. Is the charge density on each rod as seen by observer \(\mathbf{M}\) greater than, equal to, or smaller than \(\lambda_{\text {proper }}=q / \ell_{\text {proper }}\) ?

Transcribed Image Text:

Figure 27.26 Because a rod appears shorter when it is moving relative to the observer, its charge density appears larger than when the rod is at rest. rod at rest + + + + + ++ E Cproper charge density: Aproper qe proper rod moving ++++ ++ = proper proper V1-v/ charge density: A, q/b>q/lp proper