Maker Pro
Maker Pro

capacitor plate area ratio

J

Jamie Morken

Jan 1, 1970
0
Hi,

I was thinking that two couple conductors (a capacitor) is similar
to two coupled inductors (a transformer), but the difference is that
a capacitor usually has a plate area ratio of 1:1.

So if a capacitor in an AC coupled configuration is constructed with a
plate area ratio of 2:1 for the "primary" to "secondary" conductors,
will this transform an input signals voltage in a 2:1 ratio on the
secondary conductor?

cheers,
Jamie
 
S

Stanislaw Flatto

Jan 1, 1970
0
Jamie said:
Hi,

I was thinking that two couple conductors (a capacitor) is similar
to two coupled inductors (a transformer), but the difference is that
a capacitor usually has a plate area ratio of 1:1.

So if a capacitor in an AC coupled configuration is constructed with a
plate area ratio of 2:1 for the "primary" to "secondary" conductors,
will this transform an input signals voltage in a 2:1 ratio on the
secondary conductor?

cheers,
Jamie
Wrong!
The capacitance is determined by insulation characteristics, distance
between plates AND _common_ area of both plates.
In your example you would have a capacitor determined by the smaller
plate (+/- edge effects).

Have fun

Stanislaw
Slack user from Ulladulla.
 
J

John Fields

Jan 1, 1970
0
Hi,

I was thinking that two couple conductors (a capacitor) is similar
to two coupled inductors (a transformer), but the difference is that
a capacitor usually has a plate area ratio of 1:1.

So if a capacitor in an AC coupled configuration is constructed with a
plate area ratio of 2:1 for the "primary" to "secondary" conductors,
will this transform an input signals voltage in a 2:1 ratio on the
secondary conductor?
 
J

Jon

Jan 1, 1970
0
The short answer is "No".
A capacitor and a transformer operate according to two different laws
of physics. The transformer operates according to Lenz's law where v =
N(dphi/dt), i.e., the voltage coupled to the secondary is equal to the
number of turns times the rate of change of magnetic flux with respect
to time. The capacitor operates in accordance with i = C dv/dt, i.e.,
the current through a capactitor is equal to the capacitance times the
rate of change of voltage with respect to time. The capcitance of a
capacitor is roughly proportional to the overlapping area of the two
plates. I say "roughly", because there are some fringing effects near
the edges of the plates, where the electric field is not perpendicular
to the plates, but "fringes" around the edges. I hope this helps.
regards,
Jon
 
C

colin

Jan 1, 1970
0
Jamie Morken said:
Hi,

I was thinking that two couple conductors (a capacitor) is similar
to two coupled inductors (a transformer), but the difference is that
a capacitor usually has a plate area ratio of 1:1.

So if a capacitor in an AC coupled configuration is constructed with a
plate area ratio of 2:1 for the "primary" to "secondary" conductors,
will this transform an input signals voltage in a 2:1 ratio on the
secondary conductor?

I dont realy see any similarity between a capacitor and transformer, for a
start a capacitor is a 2 terminal device so the voltage is usualy referenced
to the other plate, therefore there is no 'output voltage' as such.

unrelated, ... if you charge the capacitor up and move the plates further
apart you get a voltage increase.

Colin =^.^=
 
Top