A nuclear equation shows what happens in a nuclear reaction in just the same way that a chemical equation shows what happens in a chemical reaction. Instead of looking at the atoms and how they change in a chemical reaction, a nuclear equation looks at how the individual protons and neutrons inside nuclei change.
In the same way as the total number of atoms in a chemical reaction must be balanced on both sides of the equation, so must the total number of protons and neutrons be balanced on both sides of a nuclear equation.
Gravitational Potential Energy
There are four important stored potential energies. Energy can be stored as chemical potential energy, in the chemical bonds between atoms; as nuclear potential energy, in the bonds between protons and neutrons in the nucleus of an atom; as elastic potential energy in an object that has been twisted, stretched or deformed from its normal size or shape. Energy can also be stored as gravitational potential energy.
Gravitational potential energy is the energy that an object has because of its mass and its position in a gravitational field.
The Effect of Wavelength
There’s more to light than just the rainbow of colour that we see around us.
All of the colours and images we see are just a small part of one continuous series of waves called the electromagnetic spectrum.
We owe our use of the word spectrum, which means ‘appearance’ in Latin, and our earliest knowledge about it to Isaac Newton who published a very famous book, called Opticks, way back in 1704. We’ll hear more about Newton when we look at the visible part of the spectrum later.
In this chapter we’ll look at seismic waves, how they’re produced and some of the geological events that cause them. We don’t often think of the Earth as being in any way elastic. We even use sayings like ‘solid ground’ and ‘solid as a rock’, but these are only really relevant in the sphere of our own experience. As is common in science, the behaviour we experience from objects and materials, things that we take for granted, are actually not as they appear on a large or a very small scale or in some cases over a long period of time. It turns out that the Earth is sufficiently elastic to work well as a medium for the propagation of waves.