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igcse physics notesprinted 116 · PDF 116
124 pagesrevision 46936
printed 116 · PDF 116
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In an electric field, gamma rays pass through straight because they have
no charge. Alpha particles have positive charge so they get attracted to the
negative plate but due to greater mass require more force to be pulled to
the plate which is why they travel for longer than beta particles, which
almost immediately go to the positive plate due to low mass and a negative
charge.
In a magnetic field, we can use Fleming's left hand rule to find out where
the particles will go. Since gamma rays have no charge they pass straight
through. Alpha particles will go upwards according to the rule and beta
particles will go downwards because the direction of current is opposite that
of an alpha particle since it is negative.
Ionizing effects
The ionizing effect of an alpha particle is greatest, then beta and then
gamma.
This is because an alpha particle has the most mass out of the three of
them and thus has the most kinetic energy so when it collides with an air
molecule it is more likely to knock one of the electrons out of the air
molecule. It also has the most charge because it contains two positively