According to Larmor, accelerated charges will radiate power (Watts): Larmor
So that means if electrons travel in circle then they will endlessly radiate power because of their constant acceleration.
Suppose we have a current going through a circular coil and connected to itself so the current runs forever. If we want the radiation generated by such an infinite coil then we have:
$$ \nu =\frac{\sqrt{\frac{c}{{{\epsilon }_0} h}} \left| x\right| }{\sqrt{6}\, \sqrt{{\pi} }\, \left| r\right| } $$
Where:
- $a = c^2/r$ (assuming electrons travel at c)
- $q = 1\;\mathrm{C}$ (Coulomb)
- $h$ = Planck's constant (in Joules seconds)
This seems like a strong radiation for such a small current: EM Spectrum
How is this possible?