If a 20 W Laser Beam,which Has an Initial Diameter $\times$

question 72

Multiple Choice

If a 20 W laser beam,which has an initial diameter of 2.0 mm,spreads out to a diameter of 2.0 m after traveling 10,000 m,what is the final intensity of the beam?

• A) 20 \(\times\) 10^-4 W/m²
• B) 20 \(\times\) 10^-6 W/m²
• C) 20 \(\times\) 10^-8 W/m²
• D) 6.4 W/m²
• E) 6.4 \(\times\) 10^-6 W/m²

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Definitions:

Cotton Gin

A machine invented by Eli Whitney in 1793 to separate cotton fibers from their seeds, greatly impacting the cotton industry and increasing the demand for slave labor in the southern United States.

Eli Whitney

An American inventor best known for creating the cotton gin, a machine that revolutionized the cotton industry by greatly speeding up the process of removing seeds from cotton fiber.

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A senior official within the U.S. government responsible for managing government revenue, including the issuance of currency and the administration of fiscal policies.

Revenue-Sharing

A fiscal policy wherein a central government shares part of its tax revenue with lower levels of government, such as states or municipalities.