Final answer:
The only SI unit symbolized by a Greek letter is the ohm, represented by the Greek letter omega (Ω). The ampere, the unit for electric current, is represented by the letter 'A' and does not use a Greek letter.
Step-by-step explanation:
The electrical unit of measurement that is the only SI unit symbolized by a Greek alphabet letter is the ohm. The ohm is symbolized by the uppercase Greek letter omega (Ω), and the unit is named after the physicist Georg Simon Ohm. To avoid confusion with the number 0, the Greek letter is used. One ohm is equivalent to one volt per ampere, written as 1 Ω = 1 V/A. Therefore, electrical resistance is measured in ohms, illustrating Ohm's law, which establishes a relationship between voltage (V), current (I), and resistance (R) through the equation V = IR. On the other hand, the ampere, symbolized by the letter 'A,' is the SI unit for electrical current. One ampere represents the flow of one coulomb of charge per second, indicated as 1 A = 1 C/s. It is important to note that the ampere does not use a Greek letter for its symbol.