Perhaps you have attended a party where balloons floated. A balloon filled with air does not rise above your head, but a balloon filled with helium gas rises in the air to the end of its string. What does this tell you about the density of helium?

What are atoms of the same element with varying number of neutrons

While standing outdoors one evening, you are exposed to the following four types of electromagnetic radiation: yellow light from a sodium street lamp, radio waves from an am radio station, radio waves from an fm radio station, and microwaves from an antenna of a communications system. rank these type of waves in terms of increasing photon energy.

At what time will the interfering waves have an amplitudeof zero?