Recent content by DomPhillips

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    How can we explain continuous absorption / emission?

    I am familiar with the explanations for atomic absorption and emission line spectra and how the existence of discrete, fixed energy levels can give rise to the absorption/emission lines that are seen at only very particular frequencies of EM radiation. However, I have no intuitive understanding...
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    Appearence of objects which do not reflect light

    On Facebook recently one of my friends asked the question 'What would a mirror look like if it did not reflect light?'. To this my immediate response was along the lines of: > An object which reflects no light but absorbs all light will be the darkest and most opaque object imaginable > An...
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    String Wave Velocity and Tension

    The numbers you have got seem right to be. But be careful v = 200 ms-1 not 200 Hz as you put (Hz applies only to frequency and ms-1 applies to velocity). And you should put the units for tension next to your answer for (b). Since tension is a force the units are Newtons so your answer to...
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    String Wave Velocity and Tension

    As I mentioned earlier it is easy to work out that the fundamental frequency is 100Hz. Now for the fundamental frequency we will have a node at each end of the string and there will be an anti-node in the middle - this is the simplest mode of vibration which is possible. We know that the...
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    Unusual movement of square fridge magnets

    At home I have a series of small square fridge magnets (about 25mm by 25mm and about 1mm thick). If I select two of these fridge magnets and place them together then, as you would expect, they attract one another. However the interesting observation is that sometimes the fridge magnets are only...
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    String Wave Velocity and Tension

    I'm only an A-level student but here is my analysis on the question: a) The 4th harmonic is 400Hz. Harmonics are defined as integer multiples of the fundamental frequency. Therefore the fundamental frequency is 400/4 = 100Hz. Think about what that fundamental frequency would look like on...
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    Interference of microwave transmitters of different wavelengths

    I'm struggling to see how the interference pattern would change with time since both microwaves are obviously propagating at the same velocity. Also I used wolfram alpha to try and visualize the resultant wave at different points on the 'interference pattern' I found that if I add two sine...
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    Interference of microwave transmitters of different wavelengths

    This question is about the interference pattern observed when the waves from two microwave transmitters interfere. The first parts of the question involve the wavelengths of microwaves being the same for each transmitter. For the last part the question proposes that the wavelength of one of...
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