I'm new to electronics, but I'm a physics student. I'm assuming that when someone designs a circuit, they use equations to calculate an end result (e.g. the charge on the electron) and they select components that make these changes in the circuit. For example, is the equation: ΔE=hf involved in a transmitter circuit? Is the charge on the electron equal to the frequency/planck's constant? If I'm wrong please correct me. Can someone explain how I would work out what a circuit does by using calculations?