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Difference Between “Magnitude” and “Scalar”

-- Thom | September 19, 2021

Question:

I cannot, for the life of me, comprehend the difference in application between the terms “magnitude” and “scalar”. At first I assumed they were simply interchangeable terms for the same concept, but now I’m not so certain. What is a magnitude to a scalar, and what is a scalar to a magnitude? In what sort of situations would I appropriately use each term, and in what sort of situations would it be inappropriate to use each term?

Or, in all honesty, have I simply spent too much among the non-STEM spheres of academia – and, as a result, am I simply feeling compelled to read far more weight and nuance into the difference in definition between two terms?

Thank you so much

-- Thom

Answer:

These two terms are used in multiple contexts throughout the physical sciences, but their most common usage is to describe the amplitude of a measurement. For example, a velocity is a vector measurement composed of an amplitude, such as “10 km/s”, and a direction, such as “north east”. The “amplitude” is synonymous with the “scalar” quantity of the velocity. Magnitude is often used synonymously with scalar and amplitude.

-- Jeff Mangum

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