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
![N=\frac{\lambda E_N}{h c}](https://tex.z-dn.net/?f=N%3D%5Cfrac%7B%5Clambda%20E_N%7D%7Bh%20c%7D)
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:
![N=\frac{\lambda E_N}{h c}=\frac{(520 \times10^{-9}m) (4J)}{(6.626\times10^{-34}Js) (299792458m/s)}=1.047 \times10^{19}](https://tex.z-dn.net/?f=N%3D%5Cfrac%7B%5Clambda%20E_N%7D%7Bh%20c%7D%3D%5Cfrac%7B%28520%20%5Ctimes10%5E%7B-9%7Dm%29%20%284J%29%7D%7B%286.626%5Ctimes10%5E%7B-34%7DJs%29%20%28299792458m%2Fs%29%7D%3D1.047%20%5Ctimes10%5E%7B19%7D)
It's about 6 minutes, as I seem to recall. Sort of the time for the earth to go into shadow darkness when there's an eclipse ???
Answer : The final energy of the system if the initial energy was 2000 J is, 3500 J
Solution :
(1) The equation used is,
![\Delta U=q+w\\\\U_{final}-U_{initial}=q+w](https://tex.z-dn.net/?f=%5CDelta%20U%3Dq%2Bw%5C%5C%5C%5CU_%7Bfinal%7D-U_%7Binitial%7D%3Dq%2Bw)
where,
= final internal energy
= initial internal energy
q = heat energy
w = work done
(2) The known variables are, q, w and ![U_{initial}](https://tex.z-dn.net/?f=U_%7Binitial%7D)
initial internal energy =
= 2000 J
heat energy = q = 1000 J
work done = w = 500 J
(3) Now plug the numbers into the equation, we get
![U_{final}-(2000J)=(1000J)+(500J)](https://tex.z-dn.net/?f=U_%7Bfinal%7D-%282000J%29%3D%281000J%29%2B%28500J%29)
(4) By solving the terms, we get
![U_{final}-(2000J)=(1000J)+(500J)](https://tex.z-dn.net/?f=U_%7Bfinal%7D-%282000J%29%3D%281000J%29%2B%28500J%29)
![U_{final}-(2000J)=1500J](https://tex.z-dn.net/?f=U_%7Bfinal%7D-%282000J%29%3D1500J)
![U_{final}=2000J+1500J](https://tex.z-dn.net/?f=U_%7Bfinal%7D%3D2000J%2B1500J)
![U_{final}=3500J](https://tex.z-dn.net/?f=U_%7Bfinal%7D%3D3500J)
(5) Therefore, the final energy of the system if the initial energy was 2000 J is, 3500 J
Explanation
(m) is measured in kilograms (kg)
<h2>(F) is measured in newtons (N)</h2>
<h3>acceleration (a) is measured in metres per second squared (m/s²)</h3>
Who created the theory of general relativity?:
The answer would be: Albert Einstein.
Albert Einstein developed the general relativity theory (gravitation).
The year he developed the general relativity theory or (GR) was back in 1907 and 1915. Then many other contributions after 1915.
Thanks,
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