Hey,
I always find myself fails in understanding about how devices work and I dont know why it happens all the time.
How can resistance decrease capacitance?
I might be just a student who finished only two years in EE but we're never taught that resistance can decrease capacitance.
Thanks.
Hello,
That is because resistance does not decrease capacitance,
but it can sometimes help to reduce the 'apparent' capacitance, and in
this case, the capacitive loading.
When you reduce the capacitance in a circuit you change the value
from say 100pf to 10pf, but you can reduce the loading effect the
capacitor has by connecting a resistor between the circuit under test
and the capacitor.
So you see, it's not actually lowering the capacitance, it is lowering
the apparent capacitance. Thus, when a book says, "it decreases
the capacitance", it could really mean that it just reduces the *effects*
of that capacitance, not the actual value itself.
To see how this is relevant, imagine connecting a 100pf cap across two
nodes in some circuit and the effect that cap might have on that circuit.
Next, imagine connecting that same cap in series with a 1 megohm resistor
first before connecting the combination across the same two nodes, then
think about the different effect the addition of the extra resistor has.
EE is all about ratios and what is more significant than something else.