How do electromagnets work in radio?

Answer 1

For a given load, the higher the supply voltage, the lower the load current. So, in order to avoid enormous voltage drops along the lines, high energy losses, and the need for conductors with large cross-sectional areas, transmission voltages must be very high. This is achieved using Transformers. At the consumer end of the transmission/distribution system, transformers are needed to reduce the transmission/distribution voltages to safe levels required at homes and commercial/industrial loads.

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Correct, but the question was "how", not "why".

An ordinary transformer consists of two separate coils of wire, the 'Primary' and 'Secondary' windings, on a 'Core' consisting of a stack of soft iron sheets lacquered to insulate them electrically from each other, to minimise internal losses.

As the input alternating current passes through the primary winding, it induces an alternating magnetic field in the core. In turn, that induces an alternating current in the secondary winding.

The number of turns in the coils matters: the ratio between input and output voltages, hence between their currents for the same power, is that of the turns; and the Volts and Amps ratios are inverted with respect to each other.

Hence 230V at 1A in a primary winding of 1000 turns will theoretically produce an output voltage & current of 23V at 10A in a 100 turns secondary - assuming the transformer is designed for that 230 Watts (which = Volts X Amps) power rating.

There are no direct electrical connections between the windings and the core. The link is entirely magnetic, but the induction will only work with alternating current. Having said that, there IS a type of transformer whose windings are connected electrically, but the principles are similar.

Answer 2

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