Assume (unrealistically) that a tv station acts as a point source broadcasting isotropically at 3.2 mw. what is the intensity of the transmitted signal reaching proxima centauri, the star nearest our solar system, 4.3 ly away? (an alien civilization at that distance might be able to watch x files.) a light-year (ly) is the distance light travels in one /m2

Explanation:

The intensity is related to the power and surface area by . We need to calculate the surface area of a sphere of radius r=4.3ly.

Since 4.3ly is the distance light travels in 4.3 years at 299792458m/s, we can obtain it in meters by doing:

So we have:

d) physical means can be used to separate the components of air.

the aurora is formed when charged particles emitted from the sun during a solar flare penetrate the earth's magnetic shield and collide with atoms and molecules in our atmosphere. these collisions result in countless little bursts of light, called photons, which make up the aurora.

auroras are generated by charged solar particles hitting molecules in earth's atmosphere. this usually happens in high latitudes, because our planet’s magnetic field tends to funnel these particles toward the poles. that’s why it can be experienced in northern ohio.