Name: Nuclear Chain Reaction
Uploaded: 2019-07-19
Duration: 8 min 15 s
Description: Have you ever made a row of dominoes fall by pushing the first one? It is like a chain reaction. Learn about another type of chain reaction that happens on t...

Question

What is nuclear fusion? Describe how the sun is emitting huge amount of energy (in the form of heat and light) continuously for billions of years (no reaction equations are required)?

Accepted Answer

1.When two or more light nuclei with $A < 20$ combine to form a heavier nucleus, then it is called nuclear fusion. Nuclear fission is the process occurring in various stars in our galaxy, being the reason behind the liberation of huge amount of energy and light from their surface.

2.Sun is the biggest star our solar system and the energy generation inside the sun can be explained as follows:Nuclear fusion occurs is the core of the stars, since its temperature is of the order of $10^{7} K$ .
Most of the stars including our Sun fuse hydrogen into helium and some stars even fuse helium into heavier elements.The early stage of a star is in the form of cloud and dust. Finally, due to the gravitational pull of the star itself, these clouds fall inward.

3.Thus, its gravitational potential energy is converted to kinetic energy and finally into heat. When the temperature is high enough to initiate the thermonuclear fusion, they start to release enormous energy which tends to stabilize the star and prevents it from further collapse.

4.The sun.s interior temperature is around $1.5 \times 10^{7} K$ . The sun is converting $6 \times 10^{11} kg$ hydrogen into helium every second and it has enough hydrogen such that these fusion lasts for another $5$ billion years.
When the hydrogen is burnt out, the sun will enter into new phase called red giant where helium will fuse to become carbon. During this stage, sun will expand greatly in size and all its planets will be engulfed in it.

5.The overall energy production in the above reactions is about $27 MeV$ . The radiation energy we received from the sun is due to these fusion reactions.

What is nuclear fusion? Describe how the sun is emitting huge amount of energy (in the form of heat and light) continuously for billions of years (no reaction equations are required)?

Important Questions on Nuclear Fission and Nuclear Fusion : Sources of Energy

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