In clear weather, a bright light can be seen for a long distance. In conditions of heavy fog, the visibility is greatly reduced. Which of the following explains the reduced visibility?
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OPTIONS:
- Light is refracted by water vapor in the air.
- Light is scattered by water droplets in the air.
- Light is absorbed by water vapor near the ground.
- Light is reflected by water droplets on the ground.

Light is scattered by water droplets in the air.

A 72 W navigation unit on a commercial aircraft has a 24 V power supply and uses 3 A of electric current. What is the electrical resistance of the navigation unit?
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OPTIONS:
- 4 ohms
- 8 ohms
- 13 ohms
- 22 ohms

8 ohms

Earth's core is primarily composed of which of the following materials?
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OPTIONS:
- basalt
- iron
- magma
- quartz


iron