2
lesson pretestMultiple Choice

Pretest

Question 2 • Physics I

Which is an example of radiation?

Answer
A
An ice pack is placed on a knee, and the knee cools down.
B
A rock is warmed by an ultraviolet heat lamp.
C
Cold salt water sinks to the bottom of the ocean.
D
Hot coffee in a mug causes the mug to warm up.

Explanation

Radiation transfers energy through electromagnetic waves, so it does not require direct contact or moving fluid. An ultraviolet heat lamp emits radiation that warms the rock, making B the correct choice. Cold salt water sinking is convection, while the ice pack and the mug warming involve heat transfer by direct contact (conduction).

AI-written and checked against the verified answer.

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