From the curve on the graph we can see, when y=50 x=4.5
the unit of x-axis is in "billions of years", so the answer is 4.5 billions of years
Answer:
Explanation:
The energy of a photon is given by the equation
, where h is the <em>Planck constant</em> and f the frequency of the photon. Thus, N photons of frequency f will give an energy of
.
We also know that frequency and wavelength are related by
, so we have
, where c is the <em>speed of light</em>.
We will want the number of photons, so we can write

We need to know then how much energy do we have to calculate N. The equation of power is
, so for the power we have and considering 1 second we can calculate the total energy, and then only consider the 4% of it which will produce light, or better said, the N photons, which means it will be
.
Putting this paragraph in equations:
.
And then we can substitute everything in our equation for number of photons, in S.I. and getting the values of constants from tables:

During the daytime, I have mostly line symmetry.
During the night, I often have almost spherical symmetry.
Answer:
The last one makes the most sense as they combine two like things that are easy to visualize
Explanation: