19.3. Electrical Power Transfer http://www.ck12.org
FIGURE 19.12
A common transformer.Answer: Feel the transformer and you’ll have a hint!
The heat you feel is Joule heating. The transformer is not very efficient. In fact, 75% of the available energy appears
transformed into heat.
A good many of the small transformers found in everyday electrical iterms, such as radios, televisions, and home
computers, are power transformers. These transformers are used to convert the alternating voltage and current from
a wall outlet into direct voltage and current. Many common electrical items use only direct voltage and current.
For example, a portable radio which uses batteries operates on DC voltage and therefore also requires a DC voltage
when plugged into an outlet.