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These Bitesize pages will help if you need to recap on the basics of magnets. A magnetic field is produced whenever current flows through a wire. The magnetic field is represented by a series of concentric circles around the wire, as shown below. Magnetic field lines around a current carrying wire. image: physick wiki The direction … Read more
from mrmackenzie
An electric field can be used to accelerate charged particles. Conservation of energy tells us that the work done by the field is equal to the change in the particle’s kinetic energy. The speed of the particle can be determined if its charge and the accelerating voltage are known. These notes show how to perform the calculation. … Read more
from mrmackenzie
At the end of Our Dynamic Universe, we considered big things like stars, galaxies and the Universe itself. Now the Particles and Waves unit brings us to particles so small we need groups of them just to make a single atom. Is there a connection? Why do we study particles? from mr mackenzie on Vimeo. The Standard Model An elementary … Read more
from mrmackenzie
It’s complicated and cosmologists are not certain. One of the issues is only being able to see about 4% of the mass in the universe – the stars, planets, gas and dust. About 25% of the mass of the universe is Dark Matter. It’s “dark” because it doesn’t emit light that enables us to see … Read more
from mrmackenzie
You might remember that we looked at some paradoxes when we studied special relativity earlier this term. Here is another situation where a paradox can arise. The German astronomer Heinrich Olbers (1758–1840) asked why the night sky was dark. At the time, astronomers believed that the Universe was both infinite and steady state (unchanging), so … Read more
from mrmackenzie
As we worked through the diagram explaining the stages of the Big Bang model, we looked at a section of the diagram where the Universe was hot enough for nuclear fusion. At this point, hydrogen nuclei were fusing together with other hydrogen nuclei to create helium nuclei. As the Universe expanded, it cooled and further … Read more
from mrmackenzie
introduction to the Big Bang from mr mackenzie on Vimeo. Georges Lemaître’s theory of an expanding Universe, which has become known as the Big Bang, was supported by Hubble’s observations. The expanding Universe idea was challenged by influential scientists who believed the Universe was both infinite (and therefore not expanding) and steady state (unchanging). Supporters … Read more
from mrmackenzie
In the 1920s, Edwin Hubble had access to the Hooker telescope on Mount Wilson, Los Angeles. This was the largest telescope in the world at that time. His first breakthrough was the discovery of a cepheid variable star in the Andromeda nebula. This enabled him to calculate the distance to Andromeda and he quickly realised this was … Read more
from mrmackenzie
We started our study of Einstein’s special theory of relativity this week. Special relativity is tricky get your head round, so I’ve put together a collection of videos that help to explain the ideas we’re going to consider. Let’s start with a video about the speed of light. The next video follows Einstein’s thought process … Read more
from mrmackenzie
It’s complicated and cosmologists are not certain. One of the issues is only being able to see about 4% of the mass in the universe – the stars, planets, gas and dust. About 25% of the mass of the universe is Dark Matter. It’s “dark” because it doesn’t emit light that enables us to see … Read more how will the Universe end?