Nuclear Bombs

On 6 August, 1945 the city of Hiroshima in Japan experienced the horrors of nuclear warfare for the first time in the history of the world. And 3 days later on August 9, the city of Nagasaki was razed to the ground by yet another nuclear bomb. The bombings brought Japan to its knees and ended the Second World War

                          

 Since then the world has been living in constant fear of destruction. The nuclear bomb has been called the most destructive weapon to have ever been made by mankind. From a scientist’s perspective it is an extremely interesting study. What immediately comes into our mind when we think of an atom bomb (as it is popularly called)? We think of a huge mushroom cloud forming over the site of explosion. Why does this mushroom cloud form? What makes these bombs so destructive? These are some of the many questions that have to be answered.

A nuclear weapon is a destructive weapon that derives energy from a thermonuclear reaction. It uses the energy taken from the nuclei of atoms and transforms it to incredible amounts of heat and light. There are two main types of nuclear bombs, namely nuclear fission bombs and nuclear fusion bombs. Nuclear fission bombs were the types of bombs dropped on the Japanese cities of Hiroshima and Nagasaki. The nuclear fusion bombs were developed much later and are much more powerful than fission bombs. These have never been used in warfare. It is said that one fusion bomb is equivalent in destructive capacity to around 700 fission bombs. The fusion bombs are also called hydrogen bombs.

Though both the fusion and fission bombs are called nuclear bombs, they both follow two different processes. The nuclear fission bombs are based on the principle of (no prizes for guessing ;-) nuclear fission while the fusion bombs use the principle of nuclear fusion.

Fission is the process of splitting up of a large nucleus into two or more smaller nuclei on the impact of an energetic neutron. This is accompanied by the release of extremely high amounts of energy. Generally a uranium nucleus is used in fission bombs. When the nucleus is bombarded by a neutron, it breaks into two nuclei, one Krypton and one Barium nucleus along with the release of three more neutrons. Each neutron in turn splits up a uranium atom. This results in an uncontrolled chain reaction culminating in a catastrophic explosion.

Nuclear fusion on the other hand involves the fusing of a deuterium nucleus and a tritium nucleus  to give a helium nucleus accompanied by a free neutron. This releases a much higher amount of energy than nuclear fission. But nuclear fusion is much tougher to attain on earth because the activation temperature for this reaction can only be attained by means of a nuclear fission reaction. The sun releases all its energy due to nuclear fusion reactions of hydrogen to form helium.

Now, we come to the question of the mushroom cloud, the worldwide symbol of horror connected to the nuclear bomb. Why does this mushroom cloud form?

                When the bomb detonates at ground level, the surrounding areas of up to 3 kilometre radius are vaporised due to the heat of explosion. The resulting hot gases and debris become lighter than the surrounding air and rise up at an extremely high speed . This forms the stem of the mushroom. Then as the speed of the hot gases slows down, they expand outward slowly thus giving rise to the shape of a mushroom. The mushroom head stops expanding when it reaches a height where its density is equal to the density of the surrounding air.                                        

On a historical note, nuclear bombs were an important factor in escalating tensions between the United States of America and the USSR during the Cold War. Both the countries constantly threatened to “display” their nuclear power to the other country, throwing the whole world into confusion, because if there is any sure shot method to destroy all human civilisations on the Earth, nuclear war is the way. Presently all countries are following processes of decreasing their nuclear arsenal.

Why am i saying that a nuclear war will destroy the world? Experts have conducted extensive research and found out what will happen in case of a nuclear war. If a sufficiently large amount of nuclear bombs (around 50) are detonated around the world, the huge fires following the nuclear explosions will lift enormous amounts of ash into the atmosphere. This will block most of the sunlight from reaching the earth’s surface and thus kill all the plants which are dependent on sunlight for their daily food. When all the plants die, the whole ecosystem collapses because all animals directly or indirectly depend on plants for sustenance. The global temperatures will drop, plunging the earth’s fragile ecosystem into another ice age. Millions of people will die from the explosions themselves and the unlucky ones who survive will have to bear the horrible effects of radiation.  “And the living prayed for death “. This will be the situation in case of a nuclear war. Thus we can see that nuclear weaponry is an extremely dangerous tool and has to be governed responsibly. After all

WITH GREAT POWER COMES GREAT RESPONSIBILITY!!!

BY

BHARAT, NSS VOLUNTEER