Beta-plus decay, hadrons and quarks
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The teaching part (1 min) is free to watch. A free account opens the whole lecture: 3 practice questions, 4 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- A proton that turns into a neutron
- Checking a beta-plus equation
Read the transcript of the teaching part
Last time
Before we start: last time, in Beta-plus decay and antimatter, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
A proton that turns into a neutron
A free proton is stable. Inside a nucleus with too many protons, though, a proton can turn into a neutron. The weak interaction changes an up quark into a down quark, and the nucleus sheds a positron and a neutrino. The quark picture lets us check every step.
Checking a beta-plus equation
Fluorine-18 has nine protons. It decays to oxygen-18, with eight, plus a positron and a neutrino. Check the nucleon number: eighteen equals eighteen plus zero plus zero. Check the proton number, which here means charge: nine equals eight plus one plus zero. The quark change is up to down, due to the weak interaction.
Chapter 11.4: Beta decay
- Beta-minus decay and the neutrino 5 min
- Beta-plus decay and antimatter 6 min
- Beta-plus decay, hadrons and quarks 5 min
Also for A Level Physics 9702
Which topics come up most in A Level Physics 9702 past papers, counted from every paper since 2004: Paper 1 topic frequency, Paper 2 topic frequency.