A Technological Application of Physics (Junior Cert Science): Revision Notes
A Technological Application of Physics
What is technology?
Physics helps us understand how and why everyday things happen in our world. Technology means using scientific knowledge to solve practical problems and create useful things.
If you were asked to name examples of technology in your life, you might think of computers, calculators, electric cars, the internet, or mobile phones. The people who developed these technologies in the past were called inventors. Today, technology development is more organised, with large companies employing teams of people to do different tasks.
Modern technology development involves diverse teams including:
- Mechanical and electronic engineers
- Software development engineers
- Researchers
- Many other specialists working together
Let's explore the development and use of an important technology: nuclear fission.
The discovery of radioactivity
In , Henri Becquerel, a French scientist, was studying the radiation emitted from uranium salts when exposed to sunlight. During his experiments, he discovered radioactivity.
Henri Becquerel was a French physicist and engineer. He discovered radioactivity in and won the Nobel Prize for Physics in , sharing it with Marie and Pierre Curie for their work on the study of radioactivity.
The discovery of nuclear fission
Otto Hahn, Lise Meitner, and Fritz Strassmann began performing experiments on uranium in early .
Their key discoveries were:
- When a neutron was fired at a uranium nucleus, two smaller nuclei were produced
- It appeared that the uranium nucleus had been split in two by the neutron
- This splitting process is called nuclear fission
Nuclear fission is the splitting of a large nucleus into two smaller nuclei with the release of a large amount of energy.
Further experiments on fission showed that fission produces neutrons. These neutrons could cause further nuclei to split by fission.
The chain reaction
When neutrons are released during nuclear fission, they can strike other uranium nuclei nearby. These neutrons cause further fission of nearby nuclei, producing more neutrons and causing even more fission. This is called a chain reaction. Once a reaction has started, more and more energy is released as the reaction continues on and on.
Understanding the Chain Reaction:
Step 1: One neutron hits a uranium nucleus → fission occurs
Step 2: This fission releases 2-3 new neutrons
Step 3: These neutrons hit more uranium nuclei → more fission occurs
Step 4: Pattern continues: (doubling pattern)
Result: Massive energy release as the reaction multiplies rapidly
How nuclear fission was developed into a technology
Many scientists realised that this reaction could be used to make a very powerful bomb, an atomic bomb.
In , the USA developed the Manhattan Project to build the world's first atomic bomb. Before World War Two ended, the USA employed many of the world's best nuclear scientists. However, some of them, such as Albert Einstein, emigrated from Germany primarily because they were Jewish.
The USA invested heavily in the project in case the Nazis were planning their own atomic bomb.
The development of atomic weapons
In July , the first atomic bomb named Trinity was tested in the New Mexico desert. Two more atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki in August . These bombs brought a quick end to World War Two.
The atomic bombings of Hiroshima and Nagasaki demonstrated the devastating power of nuclear fission technology and marked a turning point in both warfare and world history.
Scientists have been involved in the further development of nuclear fission for the purposes of nuclear reactors to produce electricity and nuclear weapons. Nuclear power plants use a controlled nuclear fission reaction to produce steam to generate electricity.
Modern Applications of Nuclear Fission:
Submarines, space probes, and aircraft carriers use fission reactors as their main source of energy. This is because the fuel source can last for many years without being replaced.
Scientific impact of fission
Scientists are still interested in nuclear research and radioactivity. Nuclear fission was found to be a source of huge quantities of energy. As already mentioned, the technology of nuclear fission was used in atomic weapons and in nuclear power stations to generate electricity.
Nuclear fission is non-renewable. We will eventually run out of uranium, which is the raw material that is essential for the long-term operation of nuclear fission power stations.
Nuclear fission power stations may eventually be replaced by a different nuclear technology called nuclear fusion.
Societal impact of fission
The invention of the atomic bomb brought World War Two to a quick end in . However, thousands of innocent people were killed in Hiroshima and Nagasaki when an atomic bomb was dropped on each city, mostly from the heat and explosions, not from radioactivity. In addition, many buildings were flattened and many more damaged.
After World War Two, there was a race between the USA and Russia to build more and more nuclear weapons. This led to the Cold War, which heightened secrecy and tensions between Russia and the West. However, the tensions were so great that at times it seemed like there would be a nuclear war between the two countries.
Eventually, Russia and the USA agreed that this arms race had to stop and that missiles on both sides would be destroyed.
The United Nations regulates the production of nuclear weapons and tries to discourage other countries from creating them. However, some countries still wish to create their own nuclear weapons.
Society has benefited from the huge amounts of energy that nuclear reactors can make available for electricity production.
Environmental impact of fission
Fission reactions do not produce carbon dioxide or other gases. Therefore, they do not make any significant impact on global warming and climate change.
However, fission reactors produce toxic nuclear waste that can remain dangerous for thousands of years. This has to be stored safely.
Major Nuclear Accidents:
There have been leaks of radioactivity from:
- Fukushima in Japan
- Chernobyl in Ukraine
- Three Mile Island in the USA
Each leak has contaminated farmland, affected water supplies, and caused cancer in animals and humans.
Nuclear fission power plants do not contribute to the greenhouse effect, as the method used to generate electricity does not produce greenhouse gases.
Key Points to Remember:
- Radioactivity was discovered by Henri Becquerel in in France
- The energy that originates from the nucleus of the atom is called nuclear energy
- Otto Hahn, Lise Meitner, and Fritz Strassmann discovered nuclear fission in
- Nuclear fission is the splitting of a large nucleus into two smaller nuclei with the release of a large amount of energy
- Fission has had a great scientific impact, as large amounts of energy can be obtained from a small amount of nuclear material
- Nuclear fission has had an enormous societal impact due to the development of nuclear weapons and nuclear power stations, which supply vast amounts of electricity
- Nuclear fission has had a serious environmental impact, as nuclear waste has to be stored in a number of nuclear power stations
- Nuclear fission power plants do not contribute to the greenhouse effect, as the method used to generate electricity does not produce greenhouse gases