SS: Deflection of radioactive particles

Deflection of radioactive particles in an electric field 

 Deflection of nuclear radiation by electric field

In the diagram above, a radioactive source is placed at one end of an electric field. The behaviour of the three types of emission in an electric field:

  • The α-particles behave like positively charged particles and they are deflected towards negative plate in a parabolic path.
  • The β-particles behave like negatively charged particles and are deflected towards positively charged plate. β-particles show much greater deflections than α-particles because of their lower mass.
  • The γ-rays show no deflection in the electric field and travel in a straight line as they have no charge.


Deflection of radioactive particles in a magnetic field



The figure above illustrates the behaviour of the three types of emission in a magnetic field. (The magnetic field is coming out of the page as denoted by the dots.)

  • The α-particles and β- particles are deflected in directions given by Fleming’s left hand rule.
  • α-particles are positively charged. The direction of movement of α-particles can be considered as in the direction of conventional current flow (i.e. left to right). Therefore, the force on them must be towards the bottom.
  • β-particles are negatively charged. The conventional current flow is in the opposite direction to the movement of β-particles (i.e. right to left). Therefore, the force on them must be towards the top.
  • γ-rays are not affected by the magnetic field and they travel in a straight line.


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2 thoughts on “SS: Deflection of radioactive particles”

  1. I think your “Deflection of radioactive particles in a magnetic field” diagram is backwards. A positive particle would be deflected to the left when the magnetic field is going IN not OUT as the diagram suggests. Conventionally, Xs are used to represent fields going in and Dots to represent out. I am not certain of this as I am new to the topic but it does conflict with most of the other images of this I can find


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