- #1
Jonnyto
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Homework Statement
A capacitor is to be designed to operate, with constant capacitance, in an environment of fluctuating temperature. As shown in Fig. 23, the capacitor is a parallel-plate type with plastic "spacers" to keep the plates aligned. (a) Show that the rate of change of capacitance C with temperature T is given by
dC/dT= C[dA/AdT - dx/xdt]
where A is the plate area and x the plate separation. (b) If the plates are aluminum, what should be the coefficient of thermal expansion of the spacers in order that the capacitance not vary with temperature? (Ignore the effect of the spacers on the capacitance)
Homework Equations
C=Q/V C=εA/d
The Attempt at a Solution
I have no idea how to approach the problem. So far I can only tell that the temperature is causing the area change and I'm assuming that it's also causing the plates to move away or towards each other.