Why does a transformer require alternating voltage?

current is induced in the secondary side by a changing magnetic field. If one wants a continuous output, then the changing magnetic field has to continuously change, thus, alternating current.

A transformer requires alternating voltage because of the fundamental principle of electromagnetic induction. Electromagnetic induction occurs when a changing magnetic field induces a voltage or electric current in a conductor. In a transformer, this principle is employed to either increase or decrease the voltage level.

Here's why alternating voltage is necessary for a transformer:

1. Magnetic Field Generation: A transformer consists of two separate coils, known as the primary and secondary windings, which are wrapped around a common iron core. To generate a magnetic field in the core, the primary winding is connected to an alternating current (AC) source.

2. Magnetic Field Induction: The alternating current flowing through the primary winding creates a constantly changing magnetic field around the iron core. This changing magnetic field induces an alternating voltage in the secondary winding through electromagnetic induction.

3. Step-Up or Step-Down Voltage: The ratio of the number of turns in the primary and secondary windings determines whether the transformer steps up or steps down the voltage. By adjusting the number of turns in each winding, transformers can increase or decrease the voltage level as needed.

If a direct current (DC) were used instead of alternating current, there would be no continuously changing magnetic field, and the transformer would not be able to induce a voltage in the secondary winding. Therefore, an alternating voltage is necessary for the operation of a transformer.