DO YOU KNOW HOW OUR SUN PRODUCES LIGHT ?

Nuclear power is the only thing that gives life to our sun. Nuclear power can be produced in two ways namely nuclear fisson and nuclear fusion. In atomic power plants nuclear fisson is taking place in which uranium-235 atom splits into fast moving lighter elements. But in nuclear fusion energy is produced by fusing nuclei like hydrogen to more massive helium. This same thing is happening in our sun. Obviously it is very hard to produce energy through nuclear fusion in our earth as it requires very high temperature and pressure and also the process has to overcome the repulsion between the same positvely charged hydrogen atoms. Fusion involves low mass nuclei whose combined mass is more than the resulting fused massive nucleus. The loss of mass in the process is converted to energy according to Einstein's law of conservation of mass. E = mc^2. Here m = loss of mass in the process and c = velocity of the light.

We can simply say the nuclear fusion happening in the sun as burning of mostly found hydrogen atoms to form helium atoms. The core part of the sun which extends up to 25% of the radius from it's centre is existing with very hot temperature, about 1.5 crore degree centigrade and extreme pressure is the place where nuclear fusion is happening. But fusion won't immediately happen even at such high temperature and pressure as they are repelling with each other. Every fusion of hydrogen atoms in the sun requires many number of collisions which makes the possibility of lasting it for more than 10 billion years.

The nuclear fusion in the sun can be explained in the following steps.

1. Two protons combine to form a deuterium ( hydrogen atom with one with neutron ), a positron ( similar to electron, but positvely charged ) and a neutrino.

2. A proton and a deuterium atom combine to form a helium-3 atom ( two protons with one neutron ) and gamma ray.

3. Two helium-3 atoms combine to form a helium-4 ( two protons and two neutrons ) and two protons.

In the above said three steps of reaction helium-4 atoms are less massive than the two hydrogen or protons started in the process. The loss of mass is hence converted to heat and light energy according to Einstein's law E = mc^2

The solar energy is emitted in variety of light such as ultra violet light, X-rays, visible light,infrared, micro waves and radio waves. The total energy emitted from the sun strikes the earth and makes it warm to have all living beings. Our earth atmosphere ( ozone layer ) protects us from ultra-violet radiations.