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Starting electronics
Theoretical aspects
So what is it about a capacitor which causes this delay in
voltage between switching on or off the electricity supply and
obtaining the final voltage across it? It’s almost as if there’s
some mystical time delay inside the capacitor. To find the
answer we’ll have to consider a capacitor’s innards again.
Figure 4.15 shows the capacitor we first saw in Figure 4.1,
but this time it is shown connected to a battery which, as
we know, is capable of supplying electrons from its negative
terminal. A number of electrons gather on the capacitor plate
connected to the battery’s negative terminal, which in turn
repel any electrons on the other plate towards the battery’s
positive terminal. A deficiency in electrons causes molecules
of this capacitor plate to have a positive charge, so the two
Figure 4.15 This is the capacitor shown in Figure 4.1, but this time connected to
a battery with opposite charges built up on each plate
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