How do electric cells generate a current?
We take for granted the fact that an electric cell (or battery) will cause a current to flow through an external circuit. The current is often discussed in terms of a flow of electrons (like water through a pipe) or energy transferred between adjacent electrons (like a row of dominoes falling onto each other). It might even be explained in…
Read moreAnswers to some of physics’ biggest mysteries
Exam season is over so this seems like a good time to admit that physicists don’t know all the answers – and don’t even always agree on which of the available answers is best. The two biggest areas of disagreement are cosmology and quantum mechanics. For example; Everybody is entitled to a view on such matters but to determine the…
Read moreInstrument resolution and experimental accuracy
Uncertainties in measurements arise from the equipment used and the method employed. As the final paper for this year’s A-level Physics examination is imminent, and tests knowledge of uncertainties, it is worth taking a moment to examine the causes of uncertainty in more detail. We will do this by thinking about two example measurements; one to find the thickness of…
Read moreKnow your calculator!
When answering examination questions, it is important that your excellent knowledge of physics isn’t undermined by your calculator behaving in an unexpected way. You MUST be able to trust the answer given. But the situation is potentially complicated, not only because calculators don’t all behave the same way but also because they may not even be behaving the way you…
Read moreAt what rate is the Universe expanding?
When Edwin Hubble first used data to determine whether “nebulae” were part of our own galaxy, he found they were in fact moving away from the Milky Way at a rate proportional to their observed distance. The most distant of these objects (now known to be galaxies) were receding at the greatest speed. This in turn gave birth to the…
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