When a Sparkler Is Twirled Rapidly, People Perceive a Circle

question 10

Multiple Choice

When a sparkler is twirled rapidly, people perceive a circle of light.This occurs because

• A) the trail you see is caused by sparks left behind from the sparkler.
• B) due to its high intensity, we see the light from the sparkler for about a second after it goes out.
• C) the length of iconic memory (the persistence of vision) is about one-third of a second.
• D) Gestalt principles work to complete the circle in our minds.

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Definitions:

Magnitude

A numerical value assigned to the size or amount of a physical quantity (such as force, mass, or electric current) without regard to its direction.

Direction

A course along which someone or something moves.

Right Triangle

A triangle that contains a right angle.

90 °

In electrical terms, this often refers to a phase shift of 90 degrees, which is a quarter of a cycle in alternating current (AC) or signal waveforms, representing a right angle in geometric terms.