Electrons go round in paths peripatetic,
While resonant cavities excite the field,
Oscillations at their wavelength to yield,
And since wrong-phase electrons are quickly removed,
The process, though noisy, is greatly improved.
In WWII our magnetrons were far advanced,
So that the Luftwaffe had hardly a chance,
And so our radars helped win the war
By using the magnetron not known before.
But now that the radars have grown more refined
The magnetrons' usage has greatly declined.
Yet their efficiency is put to use good:
In microwave ovens they cook our food!