Savchenko Problem 12.1.14

Physics · electromagnetism

Problem

A charged plate whose electric field strength E, moving parallel to itself at a speed v, creates a magnetic field of induction B = vc2\frac{v}{c^2}E. Therefore, when the plate velocity decreases by dv, an "extra magnetic microfield" of induction dB = ±(dv)c2\pm\frac{(dv)}{c^2}E appears in the surrounding space. Summing up, these "microfields" give an electromagnetic wave, the electric field strength of which depends only on the plate velocity: Eizl_{izl}(t, x) = cBizl_{izl}(t,x) = cc2\frac{c}{c^2}($\frac{v}{c}_{t-\frac{x}{c}}$)E = ($\frac{v}{c}_{t-\frac{x}{c}}$)E. The t - xc\frac{x}{c} index means that when calculating the field strength at a distance x from the plate, the value of its velocity should be taken at time t - xc\frac{x}{c}. For example, the electric field strength of radiation from a plate whose velocity is v0_0 sinω\omega(t-xc\frac{x}{c}) at a distance x from the plate at time t is (v0c\frac{v_0}{c})sin[ω\omega(t-xc\frac{x}{c})]E, since the plate velocity at time t - xc\frac{x}{c} was v0_0 sinω\omega(t - xc\frac{x}{c}). Prove the validity of the formula Eizl_{izl}(t,x) = (vc\frac{v}{c}t−xc_{t-\frac{x}{c}})E for the case when the velocity v changes as shown in the figures. 298

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