Three light beams encounter a medium. One light ray is reflected, while the other two are absorbed. How can the medium be described?

Transparent
Translucent
Opaque
or Clear

In satellite communication, does the satellite...

Receive radio signals
Prevent radio signals
Send radio signals
or Reduce radio signals

How does radioactivity make it possible to understand how Earth can be so old and still have a hot interior?

Opaque

To determine the description of the medium based on the behavior of the light beams, we can use the information provided:

1. One light ray is reflected: This suggests that the medium is capable of reflecting light, indicating that it is not transparent.
2. The other two light rays are absorbed: This suggests that the medium does not allow light to pass through it fully, indicating that it is not translucent.
3. Based on the above information, the medium can be described as opaque since it reflects light and does not allow light to pass through it.

Therefore, the correct answer is opaque.

Regarding satellite communication:

In satellite communication, the satellite acts as a repeater or relay station in the sky. Its primary function is to receive radio signals from one location on Earth, then amplify, convert, and redirect these signals to another location on Earth. So the satellite receives radio signals from the ground and retransmits them to the desired location.

Thus, the correct answer is the satellite receives radio signals.

Regarding radioactivity and the age of Earth's hot interior:

Radioactive elements, such as uranium, thorium, and potassium, decay over time and release heat in the process. This heat generation from radioactive decay is known as radiogenic heat.

By studying the distribution of radiogenic isotopes and their decay products within Earth's interior, scientists can measure the amount of heat produced by these radioactive elements. This heat production helps in understanding how Earth can remain hot internally for billions of years.

Based on the observed amount of radiogenic heat, scientists can estimate the age of Earth's interior. A significant amount of radiogenic heat suggests a long history of radioactive decay, indicating that Earth can be old and still have a hot interior.

Therefore, radioactivity provides valuable insights into Earth's age and the persistence of its internal heat.