The voltage across a short is 0. It also does not store any charge. So the capacitance of a short is 0/0. However, I am told the capacitance of a short is infinite. How can this be?
Electrical – Why is the capacitance of a short infinite
capacitance
Related Solutions
Type A might be a Y5V
or a Z5U "semiconductor" capacitor. They're not only bad, they're horrible. Try to avoid ever using them. They're sort of acceptable sometimes as crappy bypass capacitors, but note that they pretty much disappear from the circuit if the temperature reaches extremes.
Regarding the bounty quest for reliability in a cheap way: to convince yourself that this is a rather difficult task to do reliably (with laboratory precision), have a look at what it entails to measure "it" for a human, e.g. in a paper that studied it for ESD-related purposes, Numerical Calculation of Human-Body Capacitance by Surface Charge Method by Osamu Fujiwara and Takanori Ikawa, doi:10.1002/ecja.10025. Quoting from the abstract:
However, the body capacitance is strongly dependent on the relationship between the ground plane and the body posture. It is therefore not clear what factors govern the body capacitance. In this paper, the static capacitance of a body standing on a ground plane is calculated by means of the surface charge method. [...] It is found that the capacitance increases as the backs of the soles of the shoes approach the ground plane, that the body capacitance at the same height (10 mm) as the soles of the shoes is 120 to 130 pF, and that it is about 60 pF if the location of the soles is sufficiently high. The computational findings are confirmed by measurement of the body capacitance.
And if you're curious about their measurement method, here are the details for that from the paper:
Figure 7(a) shows the method of measurement of the human-body capacitance and Fig. 7(b) shows its equivalent circuit. The person tested (height 168 cm, weight 68 kg) with a body shape close to the human-body model is standing with bare feet on a Styrofoam plate or a perforated acrylic plate (depth 30 cm, width 11 cm) on a metal plate in a Faraday shield. The perforated acrylic plate has 201 holes made with a drill with a diameter of 4.5 mm at random locations over the plate and with an area ratio of about 9%. In this way, the relative permittivity is effectively decreased. Under this condition, a power supply is used for charging to VB0 (= 10 V) via an analog switch (Toshiba TC4066BP). When the power supply is turned off by the analog switch, the body potential vB(t) is amplified by a low-input-impedance amplifier (with an input resistance Ri = 10.2 MOhm, input capacitance Ci = 13.6 pF) and is directed to a computer via an A/D converter. The sampling frequency of the A/D converter is 200 kHz and the quantization level is 12 bits. In the potential measurement, the metal plate is used as the ground to which the grounding connections of the measurement devices are connected. From the equivalent circuit in Fig. 7(b), the body potential vB(t) is given by
$$ \frac{v_B(t)}{V_{B0}} \simeq exp \Big[ - \frac{t}{(C_i+C_B)R_i}\Big]$$
Hence, from the potential decay characteristic, the body capacitance CB can be derived.
This is basically the same time constant method suggested by George Herold (which I upvoted a while back), but at boffin standards. Nobody measures body capacitance with regularity (even for humans), so I don't know why you expect there to be a cheap way to do it reliably... Never mind that it would probably vary quite a bit as the cat changes body position.
Also, if you hope to just do simulate it on a computer... their numerical model likely won't wont be much good for a cat because:
In addition, clothes and hair are not included in the numerical model.
For a somewhat older (but right now freely available) paper, which discusses the problems with getting accurate body capacitance measurements, see N. Jonassen's Human body capacitance: static or dynamic concept?. Reading that, one point that was salient was that the soles of the shoes are actually a major contributor to the human body model capacitance (while hair and clothing can be basically ignored). Alas, that's probably the opposite of what you can expect for the dominant element to be in a cat (in its natural state) as far as capacitance is concerned. Unfortunately bounty points on SE are rather unlikely to be a sufficient "grant" for boffins to tackle this rather different cat body model in their labs...
Best Answer
The voltage across a short circuit is zero, regardless of current.
There are three components this could be modelled as, which also have zero AC voltage across them regardless of AC current, they are
a) A resistor with zero resistance
b) A capacitor with infinite capacitance
c) An inductor with zero inductance
However, these components aren't equivalent.
At DC, a capacitor can have a steady voltage across it, storing energy, and able to deliver that energy into a load.
At DC, an inductor can have a steady current through it, storing energy, and able to deliver that energy into a load.
Obviously therefore, a short circuit only is a zero ohm resistance, as it doesn't store energy.
However, if you are doing an AC analysis, and have a large value decoupling capacitor, it's often convenient to model it as 'an AC short circuit', as its series impedance will be very small with respect to the surrounding components.