Which of the following is not a dimensionless quantity?

• A. Quality factor
• B. Relative magnetic permeability μₘ
• C. Permeability of free space μ₀
• D. Power factor

In the context of physics and engineering, a dimensionless quantity is a number without any physical units. Among the options provided, the one that is not dimensionless is:

Identifying the Non-Dimensionless Quantity

• A. Quality factor - This is dimensionless.
• B. Relative magnetic permeability μₘ - This is also dimensionless.
• C. Permeability of free space μ₀ - This has units (Henries per meter) and is not dimensionless.
• D. Power factor - This is dimensionless.

Therefore, the correct answer is C. Permeability of free space μ₀, as it has specific units associated with it.