Auroras and northern lights can be seen within the ionosphere. This is the range where cosmic and the sun's radiation are ionized.
Answer:
Atomic mass
Explanation:
The weighted average of the masses of the various isotopes of an element makes the atomic mass. This is why most atomic mass values usually have decimals.
In order to calculate the atomic mass of an element using the weighted average masses, we use the expression below:
Atomic mass = ∑

Where
is the mass of isotope i
is the abundance of isotope i
The abundance or geonormal abundance is the proportion by which each of the isotope occurs in nature.
Answer:
Light
Explanation:
The way a concave mirror works is that since it's concave, the light bounces off of each other. a convex mirror, it curved the opposite, and the mirror has no way to bounce off of itself.
Answer:
Snell's Law states
Ni sin i = Nr sin r
Judging from the question the source of the ray is in the water (directed up)
or NI = 1 / sin 49 Ni = 1.325 deg the critical angle
From inside the pond:
Nr = 1.325 * sin 45 / 1 = 94 deg
So refraction can occur outside the pond and you do not have total internal refection.