What is the electric field strength between the plates?
Saturday, March 20th, 2010 at
5:08 am
A parallel plate capacitor has a potential of 100 V across it and the plates are
1 mm apart. Calculate the electric field strength between the plates.
If the area of the plates is 1×10-4 square meters and the capacitance is 10 μF,
what is the dielectric constant, , of the material between the plates?
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E (in V/m) = V (in Volts)/d (in meters)
= 100 / 0.001 = 100,000 V/m = 100,000 Newtons per Coulomb-meter
C = ε0 εr A / d
Where ε0 is the electric permittivity of free space (can’t remember it just now), εr is "relative permittivity" or "dielectric constant" (same thing, it’s dimensionless), A is the Area of one plate in meters squared, and d is the distance between the plates. C is the capacitance in Farads.
Oh, wait I found ε0: ε0 is the permittivity of free space (= 8.85 ×10^ -12 F/m)
Just solve the equation for ε0, and plug in the other numbers.
Electric field strength = Voltage / distance between plates
E = V/d
E = 100/1*10^-3
E = 100, 000 V/m (Volt per metre) or N/C (Newton per Coulomb)