Having looked at some of the finer details for beta decay in two previous posts (Q-Value and Metastable Nuclei) it seems fitting to round-off this short series with two phenomena that involve orbiting electrons rather than just nucleons. The first effect is electron capture. As its name suggests, this is when an orbiting electron is … Continue reading Electron Capture and Internal Conversion
Technetium-99m
At first glance the decay of molybdenum-99 to produce technetium-99 is a straightforward beta process. The total number of nucleons is unchanged but the number of protons increases by one with the emission of an electron and an electron-antineutrino. The half-life for this decay is 66 hours. In the nuclear decay equation above, technetium-99 is … Continue reading Technetium-99m
Beta Decay Q-value
At GCSE level, beta decay is said to be the emission of an electron (or positron, in beta-plus decay) when an unstable nucleus transforms into a more stable nucleus. The parent and daughter nuclei are different elements with the same nucleon number (sum of neutrons and protons) but their proton numbers vary by +1 for … Continue reading Beta Decay Q-value
Nobel Prize for Physics 2025
Strange things happen in the quantum world. It’s not just the events that are strange: the ways in which they happen are also weird. Take the nucleus, for example. Things were bad enough when Ernest Rutherford proposed that the atomic nucleus was very small, very dense and packed with positive charge. But things got even … Continue reading Nobel Prize for Physics 2025
Charging a Capacitor (analysis)
Changes in charge, current and potential difference during the charging and discharging of a capacitor are all exponential-type behaviours. Specifically, the current that transfers charge to or from a capacitor (during charging or discharging respectively) is always greatest at first and declines to zero as time increases. During discharging, the charge loss and the drop … Continue reading Charging a Capacitor (analysis)
Uncertainties and Error Bars
Measurements are always uncertain: there is no such thing as a perfectly precise measurement. At the very least, the instrument used will limit the precision of the value but in many cases other factors can introduce even greater variability. It is always the greater of these two numbers (the resolution of the instrument and variability … Continue reading Uncertainties and Error Bars
How high does a spring toy jump?
Determining a spring toy’s jump height is a useful exercise in the application of physics, not only in terms of this specific example but also in highlighting contrasting approaches to answering any sort of physics question. As is so often the case, there are two possible starting points; the first is theoretical whereas the second … Continue reading How high does a spring toy jump?
How to determine voltages inside a resistor network
Resistor networks sometimes look scary but they can be solved by taking things one step at a time and applying basic circuit rules. The rules concerned are the calculations for combining series and parallel resistors, together with Kirchoff’s two laws for circuits. To combine resistors, we add their values if they are arranged in series … Continue reading How to determine voltages inside a resistor network
The Amateur Scientist
There was a time when children were encouraged to do their own experiments at home. A lucky few got chemistry sets as Christmas presents. Others might have read books covering activities that ranged from star-gazing to building crystal radios. As somebody who grew up in what was probably the golden age for young scientists, before … Continue reading The Amateur Scientist
Beta Decay and Energy Conservation
I have just finished reading an excellent book that traces various theories about beta decay in the first third of the Twentieth Century. Controversy and Consensus: Nuclear Beta Decay 1911-1934 is an editted version of the successful PhD thesis written by Carsten Jensen, who clearly had a deep passion for unravelling physics history but died … Continue reading Beta Decay and Energy Conservation
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