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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?