Far-Infrared Telescopes Have to Be Cooled,but Visible-Light Telescopes Do Not

question 7

Multiple Choice

Far-infrared telescopes have to be cooled,but visible-light telescopes do not.Why not?

• A)Far-infrared radiation is absorbed by the Earth's atmosphere.
• B)Visible-light telescopes detect light from cool objects.
• C)Far-infrared telescopes can only work in space.
• D)Telescopes are not hot enough to emit visible light.

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Definitions:

Net Exports

The value of a country's total exports minus its total imports, representing the net trade of goods and services with foreign countries over a specific time period.

Net Capital Outflow

The difference between the domestic country's total purchase of foreign assets and foreign purchases of the domestic country's assets over a specific period of time.

Currency Depreciate

A decline in the value of one currency relative to another currency, which can affect international trade and economic balance.

Purchasing-Power Parity

A theory in economics that suggests that in the absence of transportation and other transaction costs, identical goods will have the same price in different markets when prices are expressed in a common currency.