Chandra is the unsung hero of space telescopes. Far better known is the Hubble Space Telescope, which is rightly famous for the spectacular images it has produced. But Hubble was only ever intended to be one arm of a four-pronged approach to astronomical observations, another of which is provided by Chandra. Whereas Hubble produces images … Continue reading Chandra: the Universe as seen in X-rays
Shapes of Shadows
First a correction: this post is really about the shapes of the bright patches between shadows but "shapes of shadows" sounds much better so please excuse my decision to go for artistic alliteration! If you have ever walked under some leafy trees on a bright summer's day, with the sun high in the sky, you … Continue reading Shapes of Shadows
Key Facts: Electromagnetic Waves
Having previously covered waves in general (https://physbang.com/2023/04/13/key-facts-waves/) it is now time to look at electromagnetic waves in particular as this is a topic in its own right. Electromagnetic waves are created by the movement of electrons in different situations. The electrons can be moving in an electric circuit, to produce or receive radio waves, or … Continue reading Key Facts: Electromagnetic Waves
Key Facts: Waves
We can define a wave as something that carries energy from one place to another without the transfer of physical matter. To understand this definition it is useful to think about two different ways of feeling heat. In a shower, heat is created by an energy exchange inside the storage tank or shower unit and … Continue reading Key Facts: Waves
Standard Form
Every GCSE physics paper normally has at least one question with a mark for the correct interpretation or expression of numbers in standard form. This is a basic skill that is taught as part of GCSE mathematics courses but it holds a great deal of power for scientific calculations that is rarely mentioned at this … Continue reading Standard Form
More than meets the eye
Optical illusions aren't part of the school science curriculum - but they should be. We tend to believe what we see, and a lot of what we know about science is based on visual observations, but we aren't normally taught to question the evidence of our own eyes. One of the classic puzzles of astronomy, … Continue reading More than meets the eye
Focusing EM Waves
Focusing is the term that describes parallel rays of light being brought together into a single point, known as the focal point. Electromagnetic waves can be focused using either refraction (with lenses) or reflection (with mirrors). Both of these effects can be explored in the excellent geometric optics simulation that has just been unveiled by … Continue reading Focusing EM Waves
Properties of EM Waves
Electromagnetic (EM) waves are generated by the movement of electrons. In an electric circuit, visible light can be generated when electrons (a current) move through a lamp. Electric circuits can also generate infra-red waves (TV remote controls), microwaves (ovens), x-rays (medical scanners) and radio waves (aircraft ground-to-air communications). These different types of EM waves have … Continue reading Properties of EM Waves
Energy Budget
It is well known that darker surfaces heat up faster than lighter surfaces and reach a higher maximum temperature. But why? When the maximum temperature is achieved, there is a state of thermal equilibrium that is is due to a balance between the rates at which (new) energy is being absorbed and (previously) stored energy … Continue reading Energy Budget
EM Waves: Uses and Dangers
Different EM waves are used for different applications, which you are expected to be able to recall and explain. We will go through some of these uses in this article, which is unavoidably long as there is a lot of information to cover. Your exam preparation should therefore involve making summary notes from the wealth … Continue reading EM Waves: Uses and Dangers
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