Transformers do not pass direct current (DC), however they may be used to extract the DC voltage (constant voltage) from a signal while maintaining the variable component (the AC voltage). Transformers are essential in the electrical grid for shifting voltages and reducing energy loss during electrical transmission. The main use of transformers is to increase or decrease voltage levels on electricity transmission lines.
When voltage is transmitted over long distances, it must be done carefully so as not to overload the transmission line. If it were not for transformers, this would require large amounts of power at high voltage, which is expensive to transmit and difficult to handle safely. A transformer can bring the voltage down in front of the transmission line transformer, safe for the transmission line to handle, and also allow more distance between transmission station and consumer device than could otherwise be achieved with fixed voltage transmissions.
A transformer uses magnetic flux to induce voltage in another coil of wire called the secondary coil. When electric current is passed through the primary coil, a similar current flows in the secondary coil when there is a close match between the number of turns in the two coils. The amount of voltage induced in the secondary coil is always just enough to make up for the losses suffered by the primary coil. Therefore, a transformer can increase the efficiency of an electrical system. It can also reduce the required size of electrical components since circuits only have to deal with one voltage level instead of two (or more) as with multiple independent power supplies.
An alternating current power supply (AC power supply) normally takes voltage from a wall outlet (mains supply) and uses a transformer to step up or step down the voltage to the desired value. Transformers (also known as voltage transformers) are devices that are used in electrical circuits to modify the voltage of the electricity flowing through the circuit. They can be used to increase the voltage of an AC power source for use with equipment that requires a high voltage but also need low impedance (such as lights), or they can decrease the voltage of a DC power source such as a battery to reduce energy consumption.
Transformer design varies depending on application requirements. A primary purpose of a transformer is to change the voltage of an electric signal. It does this by using magnetic flux to induce voltage differences across its windings. The amount of voltage induced depends on how much magnetic flux flows through the core of the transformer. Transformers come in many sizes and shapes. They are usually cylindrical or rectangular, but other geometries are available. A typical transformer used in home electronics has a diameter of about 1 foot and a height of about 4 inches. It contains eight or more layers of wire wrapped around a central core material such as iron or steel. The number of turns around the core determines the ratio between input and output voltages. For example, if there are 100 turns on the core, then the output voltage will be 10 times higher than the input voltage. Some transformers have multiple secondary coils instead of just one.
The current is routed via transformers to boost the voltage, allowing the power to be sent across great distances. The electrical charge travels throughout the country via high-voltage transmission cables. Smaller transformers lower the voltage once further, making the electricity safe for use in our homes. The term "transformer" comes from the fact that it takes energy to operate them.
When two different voltages are involved, something must give. Either voltage will reduce, but which one? If low voltage is given as zero, then why does anything work at all? The answer is that there is always some voltage available for everything except electrons. This may seem strange, but it can be explained with an example. Let's say that I have a 9-volt battery and connect one end of a light bulb to it. The other end of the bulb is connected to ground (or 0 volts). When I turn on the battery, the bulb lights up because there is enough voltage for it to do so. However, if I were to connect both ends of the bulb to 9 volts, it would burn out immediately.
Electrons are forced through the filament of the bulb by its internal resistance. Some will escape back into the atmosphere, but most will remain within the body of the bulb. They flow through the hot wire, where they lose energy, and this heat is what allows the bulb to emit light even when not being powered.