22 Electric Fields

This page covers the electrical fields section of the course. 


22 Electric Fields Student Booklet

22 Electric Fields


Semolina and Electric Fields

22.4 Coulomb Law Challenge Questions

pHet Fields Worksheet

22.5 Uni Level Problems



Candle Flame in an Electric Field

When the E.H.T. power supply is switched on, the candle flame splits into two portions in opposite directions. The portion that is attracted to the negative plate is very much larger than the portion that is attracted to the positive plate as there are more positive ions.

The hot flame of the candle ionises the air molecules in its surrounding into positive and negative ions. The positive ions are heavier and move much slower. Thus, a larger portion of the flame follows the positive ions, moving towards the negative plate.

The negative ions are electrons and are very much lighter than the positive ions. They move faster towards the positive plate. Thus, the portion of the flame that follows the negative ions are much smaller and thinner.

This practical really does need a 25kV supply to work well.

Also remember that in a uniform electrical field E = V/d so when we move the electrodes closer they put out the flame.

At the end we can see the soot on the negative electrode.
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