# Could someone explain the physics of this circuit?

by ChromeBit
Tags: circuit, explain, physics
 P: 436 Yes radio waves and more generally electromagnetic waves are generated by oscillating electric current. Oscillating or alternating means practically the same thing, it means a quantity that varies in space and time according to some function f(x-vt). An electromagnetic wave is an oscillating electric field, together with an oscillating magnetic field. I cant analyze the circuit in detail but i believe: 1) The L1C2 circuit role is to provice the carrier signal frequency. That is an oscillating current with frequency $$f=\frac{1}{2\pi\sqrt{L1C2}}$$ which will be modulated by the microphone's oscillating current to produce the final signal that will go as input to the antenna. 2) The role of the transistor Q12N2222 is to modulate the carrier signal with the microphone's signal and produces the final current which goes to the antenna via the capacitor C3.