Write a summary for the lab
Objective
A transformer is a device used to change voltage and current. You may have noticed the gray electrical boxes often located between two houses or buildings or cylindrical containers mounted high on power poles. These boxes protect the transformers that “step down” high voltage from power lines (13,800 volts) to standard household voltage (240 or 120 volts).
How a transformer works:
The primary coil is connected to outside power lines. Current in the primary coil creates a magnetic field through the secondary coil.
The current in the primary coil changes frequently because it is alternating current.
- As the current changes, so does the strength and direction of the magnetic field through the secondary coil.
- The changing magnetic field through the secondary coil induces current in the secondary coil. The secondary coil is connected to the wiring in your home.
- [Image unavailable: Diagram of a basic transformer showing the primary and secondary coils.] Transformers work because the primary and secondary coils have different numbers of turns. If the secondary coil has fewer turns, the induced voltage in the secondary coil is lower than the voltage applied to the primary coil. This would be referred to as a Step Down Transformer. If the secondary coil has greater turns, then the induced voltage in the secondary coil is higher than the voltage applied to the primary coil. This would be referred to as a Step Up Transformer. You can use the proportion below to figure out how number of turns affects voltage:
- Transformer equation: Edit[Image unavailable: Transformer equation]
The transformer ratio is the ratio of the primary to secondary voltages in a transformer which equals the ratio of the number of loops in their coils. The turns ratio is expressed as 1 to n or 1:n.