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Capacitance and Resistance of a fluid 
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#1
Dec1108, 02:48 PM

P: 1,031

1. The problem statement, all variables and given/known data
A parallel plate airspaced capacitor has a capacitance of 100pF. It is immersed in a fluid of resistivity 10 m. Calculate the resistance between the plates. 2. Relevant equations [tex] C = \frac{\epsilon_0A}{d} [/tex] [tex] R = \frac{\rho l}{A} [/tex] 3. The attempt at a solution I seemed to get this question too easily... First of all, I said that for the fluid, the area is the area of the pates, and l is the distance d between them, then I rearranged the resistivity equation into terms of a/d: [tex] \frac{A}{d} = \frac{\rho}{R} [/tex] then I substituted this equation into the capacitance equation: [tex] C = \epsilon_0\frac{\rho}{R} [/tex] rearrange for R: [tex] R = \epsilon_0 \frac{\rho}{C} [/tex] Insert values: [tex] R = \epsilon_0 \frac{10}{100*10^{6}} [/tex] this gives a value of [tex] 8.85 * 10^{7} [/tex] Ohms Does this look correct? TFM 


#2
Dec1108, 05:20 PM

Mentor
P: 12,070

You're almost there. What does the "p" in pF mean? Hint: it's not 10^{6}.



#3
Dec1208, 05:58 AM

P: 1,031

pF is a pico Farad, I believe
Iyt is 10^12, not 6, that was illy of me  I should have remebered that 10^6 is micro TFM 


#4
Dec1208, 01:29 PM

P: 1,031

Capacitance and Resistance of a fluid
Putting in my new value for C, I get the resistance to be:
0.885 Ohms Does this look right now? TFM 


#6
Dec1308, 03:34 AM

P: 1,031

Excellent
Thanks for your Assistance, Redbelly98, Most Appreciated TFM 


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