physics confusion Posted June 10, 2011 Share Posted June 10, 2011 Hi I'm doing classes in both physics and chemistry and i've got a bit of a confusion. During Beta decay of a radioisotope, the electron is ejected from the nucleus. Why doesn't it attract to the protons, according to magnetic laws. Any help please Link to comment Share on other sites More sharing options...
swansont Posted June 10, 2011 Share Posted June 10, 2011 Hi I'm doing classes in both physics and chemistry and i've got a bit of a confusion. During Beta decay of a radioisotope, the electron is ejected from the nucleus. Why doesn't it attract to the protons, according to magnetic laws. Any help please It is (electrostatic more than magnetic), but the amount of energy it has means it will be unbound. That is, its KE + PE > 0 1 Link to comment Share on other sites More sharing options...
physics confusion Posted June 11, 2011 Author Share Posted June 11, 2011 what do you mean by electrostatic and where does the electron receive the energy from (given the laws for conservation of energy state that energy isn't capable of being created or destroyed) Link to comment Share on other sites More sharing options...
DrRocket Posted June 11, 2011 Share Posted June 11, 2011 what do you mean by electrostatic and where does the electron receive the energy from (given the laws for conservation of energy state that energy isn't capable of being created or destroyed) Electrostatic force is the repulsive force between like charges or the attractive force between opposite charges. It is what makes your hair stand up when you comb it on a dry day. It is the electric component of the Lorentz force from electrodynamics, [math]F=q(E + v \times B)[/math] , [math]E[/math] being the electric field and [math]B[/math] being the magnetic field. The electron energy comes from the same place that the electron comes from. That is the energy associated with the weak force and its carrier, one of the W bosons, the [math]W^-[/math] boson in the case of electron emission, which itself comes from a down quark converting to an up quark. At this level neither conservation of mass nor conservation of energy hold, but rather it is mass/energy that is conserved, keeping in mind the equivalence of mass and energy ([math]E=mc^2[/math]). http://en.wikipedia....wiki/Beta_decay Link to comment Share on other sites More sharing options...
physics confusion Posted June 12, 2011 Author Share Posted June 12, 2011 O.K. My problem is that given protons are positively charged and electrons are negatively charged, why don't they attract together. Link to comment Share on other sites More sharing options...
swansont Posted June 12, 2011 Share Posted June 12, 2011 O.K. My problem is that given protons are positively charged and electrons are negatively charged, why don't they attract together. They do. But a rocket is gravitationally attracted to the earth and can still escape. It's a matter of how much energy the electron (or rocket) has. Link to comment Share on other sites More sharing options...
physics confusion Posted June 13, 2011 Author Share Posted June 13, 2011 Thanks for the clarification, however, the enrgy needed must come from somewhere. Is it possible to determine the source of energy??? Link to comment Share on other sites More sharing options...
timo Posted June 13, 2011 Share Posted June 13, 2011 (edited) "Energy must come from somewhere" is your interpretation of "total energy is constant" (not a bad interpretation, but I'm a bit picky here because you're asking about processes where everyday intuition may break down). That means that the mass of the particle that beta-decayed (times c-squared) must equal the sum of a) the mass of the object after it decayed, b) the mass of the electron that is produced, c) the kinetic energy of the object after decayed, d) the kinetic energy of the electron, e) the kinetic energy of the neutrino that is also produced. All of these addends are positive, so to make this an equation, the mass of the object after it decayed must be smaller than its mass before the decay. You might interpret this as the energy coming from the mass of the decaying particle (which becomes smaller). Edited June 13, 2011 by timo Link to comment Share on other sites More sharing options...
swansont Posted June 13, 2011 Share Posted June 13, 2011 Shorter version: the rest mass of the daughter+ electron is smaller than the rest mass of the parent. E=mc^2 Link to comment Share on other sites More sharing options...
physics confusion Posted June 16, 2011 Author Share Posted June 16, 2011 Thanks for the responses. I was talking to my teacher and i'm thinking i will need to do an experiment to understand this better. No need to continue this forum Link to comment Share on other sites More sharing options...
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