Conductor problem in which the conductor consists of two parallel plates

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SUMMARY

The discussion centers on solving a conductor problem involving a vacuum diode with two parallel plates, where electrons are emitted from a cathode and accelerated towards an anode. The participants derive Poisson's equation, {\nabla}^2V=\frac{\rho}{{\epsilon}_0}, and explore the relationship between charge density, current, and electric field. They establish that in steady state, the current is independent of position, leading to a differential equation for the potential V(x) that incorporates constants and the charge density. The final equation derived is \frac{d^2V}{dx^2}= \kappa V^{-1/2}, where \kappa is a constant defined as \kappa \equiv \frac{-I}{\epsilon_0 A} \sqrt{\frac{m}{2q}}.

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  • Understanding of Poisson's equation in electrostatics
  • Familiarity with the concepts of electric field and potential difference
  • Knowledge of charge density and its relationship to current
  • Basic calculus for solving differential equations
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  • #31
gabbagabbahey said:
Yes, you now have an ODE for V(x) involving only V(x), its derivatives, and some constants; so there is your answer to part (d). For part (e) you are asked to solve this ODE for V(x), to make it easier to work with I recommend you collect all your constants into one, say,

\kappa \equiv \frac{-I}{\epsilon_0 A} \sqrt{\frac{m}{2q}}

\Rightarrow \frac{d^2V}{dx^2}= \kappa V^{-1/2}

Now, try to solve this ODE.

my only variable is V since V is a function of x . I am solving an equation for V(x). So my only problem with e is just the math since I am only rearranging all the constants to one side of the equation and V by itself on the other side of the equation .
 
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  • #32
Hint:

\frac{d^2V}{dx^2}= \frac{d}{dx} \left( \frac{dV}{dx} \right)

Rewrite
\frac{dV}{dx}

as V' and multiply both sides of the equation by V'dx then integrate from x=0 to x=d.
 

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