Question

The power output of the Sun is 4.062×1026 W. If 81.5% of this is supplied by the proton-proton cycle, how many protons are consumed per second? Give your answer in 1038 protons per second.

Answer 1

Number of protons consumed per second will be given by:

Number of protons consumed per second = efficiency*total power*protons used in cycle/energy released

Using given values:

Total power = 4.062*10^26 W

energy released in single proton-proton cycle = 26.7 MeV = 26.7*10^6*1.6*10^-19

protons used in proton-proton cycle = 4

efficiency = 81.5% = 0.815

So,

Protons consumed per second = 0.815*4.062*10^26*4/(26.7*10^6*1.6*10^-19)

= 3.099*10^38

= 3.1*10^38 protons per second

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Extra Information:

energy released in single proton-proton cycle = 26.7 MeV (this values is taken from reference book college physics textbook)

proton-proton cycle is

2e + 4¹H ----> ⁴He + 2v_e +

Energy released = dm*c^2 = (4*mass of proton - mass of helium)*c^2