1. Transformers They’re more than meets the eye

2. A transformer is made of 2 coils, near each other but not touching. Many times one is inside the other, and they may have an iron core to better align the magnetic field. One coil is connected to a power source (primary) and one coil is connected to a load (secondary).

3. The primary must be connected to alternating current. As the current builds, the magnetic field in the primary grows. That means magnetic field lines will cross the secondary and act as a generator. That will induce a current in the secondary. Because the current is always changing in an alternating current circuit, the magnetic fields are constantly moving, and that keeps a current flowing in the secondary. The current lags by 90° in the secondary.

4. The ratio of the number of turns in the primary to the number of turns in the secondary is the same as the ratio of the voltage in the primary to the voltage in the secondary. VpVp VsVs NpNp NsNs =

5. The current has an inverse relationship. V p I s V s I p =

6. There are two types of transformers, a step-up and a step-down. A step- up transformer changes lower voltage into higher voltage, and a step-down changes high voltage into low voltage. There are transformers on electrical lines and on plug-ins.

7. A step up transformer has 300,000 turns in the primary and 650,000 turns in the secondary. If the primary is hooked to a 24 V power supply, what voltage is in the secondary?