Final answer:
The indicator of the magnitude of a vector is the length of the arrow, with the larger length representing a greater magnitude, and the arrow's direction indicating the vector's direction.
Step-by-step explanation:
When illustrating vectors, the indicator of the magnitude of the vector is the length of the arrow. The arrow used to represent a vector reflects the vector's properties, with its length being directly proportional to the magnitude of the vector. That means the longer the arrow, the greater the magnitude. The vector's direction is denoted by the direction in which the arrow points. For precise representation, a scale is typically utilized so that the length of the arrow can be translated into the vector's actual magnitude. For example, if a scale of 1 cm = 2 N is chosen, a 20 N force vector would be represented by an arrow 10 cm long in the chosen direction.
It is important to note that the magnitude of a vector is always a positive scalar quantity and is indicated by the length of the vector's arrow. If only the magnitude is of interest, sometimes the arrow may be omitted. However, for a proper vector representation, both magnitude and direction are crucial, and the arrow notation indicates these properties succinctly.