Is it placed merely on single words? No. It may be placed on individual words, phrases, or sentences.
Does it consist of force alone? No. Emphasis consists of time, pitch, force, quality, and location.
Time. By time is meant the rapidity of utterance; as,
With noiseless foot he paces the lonely hall, half lighted by the moon—he winds up the ascent of stairs, and reaches the door of the chamber.
—Daniel Webster
The idea is here brought out by means of the slow, measured manner in which the murderer is described noiselessly passing through the lonely hall and winding up the stairway. If this passage were quickly and violently spoken, a mis-interpretation would be given it. Time, in this instance, gives emphasis to the thought.
The light of the newly kindled sun, indeed, was glorious. It struck upon all the planets, and waked into existence their myriad capacities of life and joy. As it rebounded from them, and showed their vast orbs all wheeling, circle beyond circle in their stupendous course, the sons of God shouted for joy.
—Horace Mann
This passage is also made emphatic by the time employed. It requires rapidity of utterance in order to express the ideas of the awakening of life and the joy of man.
Pitch. By pitch is meant the tone of voice employed—its height or depth; as,