Hello folks. This is Sandeep. I have many lingering doubts in physics that I am here to get cleared. This has become more of an issue ever since I decided to teach physics to my young nephew. My first question pertains to electromagnetic waves and the conservation of energy. Consider an AC circuit. It's power consumption P1 is the heat loss from resistance. The circuit will have an electrical and magnetic field associated with it. Let us now introduce a coil in the electrical and magnetic field of our circuit. We know that an electric current will be induced in the coil. There will be some power consumption in the coil, in the form of heat loss, due to the resistance of the coil. Let us call it P2. My question is this: What is the source of the power P2? It may be argued that the coil will have to have its own power source, but there are some crystal receivers, which do not have their own power source.