Transformers

This toy train is powered by an electric motor housed inside its engine. The voltage required by the motor in order to operate is about 15 volts. When the power cord is connected to a standard 110 volt AC outlet, however, only the required 15 volts is applied to the electric motor.

What is it that accounts for this reduction in voltage? This force at light 2 requires a certain amount of voltage before it will operate. The voltage required in this case though is several hundred volts.

Just like the train however when its power cord is connected to a 110 volt AC outlet, the required several hundred volts is applied to the light. What is it that accounts for this increase in voltage?

The answer to both of the questions just posed for you and also the subject of this lesson is the transformer. Now just what is a transformer? Well basically we can say it's a device that does just what its name implies.

It changes or transforms voltage. It's a transformer reduces the voltage as in the case of the train it's called a step down transformer. Whereas if the transformer increases the voltage as in the case of the fluorescent light it's called a step up transformer.

The ability of the transformer to transform voltage can be understood best if we first examine an important phenomenon in electricity, the magnetic field. When electric current passes through a wire, an invisible band of magnetic force is set up around the wire.

In the case of direct current, this magnetic field expands to a certain point and stays there. Except of course it's traveling around the wire all the time. For instance, if you were to grasp the wire in your left hand and extend your thumb in the direction the current is traveling, the magnetic field will be circling the wire in