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What Is the Difference Between a Transformer & Amplifier?

Transformers and amplifiers are commonly-used components in a variety of electric circuits. Both components are capable of altering the voltage levels in a circuit. However, the devices alter voltage through very different processes. In a transformer, the output power equals the input power. In an amplifier, the output power can be much higher than the input power. Consequently, transformers and amplifiers have different areas of application.

How Transformers Work
- Transformers consist of two independent coils of wire at different lengths wound around a common magnetic core. As alternating current travels through one coil, it creates a fluctuating magnetic field in the core. The other coil experiences the fluctuations in the common magnetic core. However, because it has a different number of coils, the voltage induced by the magnetic field is different from the input voltage. Though the voltage changes, the power transferred through a transformer remains the same. Electrical power equals voltage times current. If the output voltage of a transformer is greater than the input voltage, the output current must be less than the input current.
Applications of Transformers
- Transformers are essential to power supply circuits. Standard electrical outlets in the United States provide 120 volts of power. Many devices operate at far lower voltages, requiring a transformer to convert the voltage to a more suitable value. Transformers can also be used to raise the voltage. For example, a step-up transformer can convert a 120-volt power supply to 230 volts, suitable for use with European devices.
How Amplifiers Work
- Amplifiers can be made out of a number of different materials, but their basic principle is the same: an input signal controls a larger output signal, resulting in a voltage gain. Voltage gain is the ratio of output voltage to input voltage. In order to enact this voltage gain, an amplifier requires an external power source. An amplifier can create an increase in voltage without a corresponding decrease in current, resulting in a power gain.
Applications of Amplifiers
- Amplifiers can be made of a vacuum tube, a transistor or a chip called an op-amp. All of these components can be used in audio amplifiers. Furthermore, amplifier circuits can manipulate feedback loops in order to create oscillating circuits, forming the basis for a number of signal generating circuits. Amplifiers have a wide variety of other uses, wherever active control of voltage is required.

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