Can Any Genius Answer My Questions .can Any Body.

[mohdfasieh]

QUESTION:

1: Stars are known to flicker.Estimate the number of photons entering the eye of an observer when he looks at the star of first apparent visual magnitude.Such a star produces flux on the surface of the Earth of 10(exp)-6
lumens/m(exp)2. One lumen is 0.00a6 watts.Why do stars flicker ?not the plannets.

2:Calculate the number of carbon atoms released on burning petrol (octane) and natural gas (methane) to produce the same amount of energy of one joule.1 kg of petrol produces about 44 x 10(exp)6 of energy wheras 1 kg of natural gas would release 55 x 10(exp)6 Joules.What is the ratio?From the point of view of preserving environment,which is better to use?

 

[Nereid]

Please do NOT cross-post.

 

[sir-pinski]

RESPONSE:

1. Estimating the number of photons entering the eye of an observer when looking at a star of first apparent visual magnitude is a complex calculation that involves several factors such as the distance of the star from Earth, the size of the star, and the sensitivity of the observer's eye. However, we can make an estimation based on the given information.

Assuming the observer's eye has an aperture of 1 cm^2, and using the formula for luminous flux (F = P/A), where F is the flux, P is the power, and A is the surface area, we can calculate the number of photons entering the eye.

First, we convert the given flux of 10^-6 lumens/m^2 to watts/m^2 by multiplying it by the conversion factor of 0.0006 watts/lumen. This gives us a flux of 6 x 10^-10 watts/m^2.

Next, we can calculate the power of the star by multiplying the flux by the surface area of the observer's eye (1 cm^2 or 0.0001 m^2). This gives us a power of 6 x 10^-14 watts.

To convert this to the number of photons, we need to use the formula E = hf, where E is the energy of a photon, h is Planck's constant (6.626 x 10^-34 Joule seconds), and f is the frequency of the light.

Since the frequency of visible light is around 4.3 x 10^14 Hz, we can calculate the energy of one photon as 1.44 x 10^-19 Joules.

Finally, we can divide the power of the star (6 x 10^-14 watts) by the energy of one photon (1.44 x 10^-19 Joules) to get the number of photons entering the eye. This gives us an estimation of 4.17 x 10^5 photons.

As for why stars flicker, it is due to the Earth's atmosphere causing fluctuations in the amount of light reaching our eyes. These fluctuations are caused by turbulence in the atmosphere, temperature differences, and other factors. Planets do not flicker as they do not emit their own light and are not affected by the Earth's atmosphere in the same way as stars.

2. To calculate the number of carbon atoms released on burning petrol and natural gas to produce one jou