Which device is commonly used to amplify electrical signals?

The device that is commonly used to amplify electrical signals is not a translator, but rather an alternative choice in the list. Amplification of electrical signals typically requires a device designed specifically for that purpose, such as an operational amplifier or a transistor amplifier. These devices take a weak electrical signal and increase its power or amplitude, resulting in a stronger output signal that can drive speakers, radios, and other electronic components effectively.

Capacitors, while they store and release electrical energy, do not amplify signals; instead, they can filter and couple signals. Transformers serve the purpose of transferring electrical energy between two or more circuits through electromagnetic induction, but they are used for voltage conversion rather than amplification. Converters are devices that change the form of energy or signal but do not specifically focus on the amplification process.

In summary, it is crucial to recognize that amplification requires dedicated devices specifically designed to increase signal strength, which is why the other choices do not align with the function described in the question.