- #1
DracoMassakin
- 2
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So the problem is "An electric field of 7.85*10^5 V/m is desired between two parallel plates, each of area 38.0 cm^2 and separated by 2.45 mm of air. What charge must be on each plate?"
Relevant equations: V=-E*d, C= (E0*A)/d, C=Q/V
I have calculated the voltage by taking V=-E*d=(-7.85*10^5 V/m)0.00245m= -1923.25V
Then I found the capacitance of the plates C= (E0*A)/d , (E0= Vacum Permativity) and got
C=((8.85*10^-12)0.0038 m^2)/0.00245m= 1.373*10^-11 F
But for the final calculation to find the charge I took Q= C*V = (1.373*10^-11 F)*-1923.25 V= -2.641*10^-8C So do I need to include the negative in that final calculation to get a negative charge or do I leave it out?
Relevant equations: V=-E*d, C= (E0*A)/d, C=Q/V
I have calculated the voltage by taking V=-E*d=(-7.85*10^5 V/m)0.00245m= -1923.25V
Then I found the capacitance of the plates C= (E0*A)/d , (E0= Vacum Permativity) and got
C=((8.85*10^-12)0.0038 m^2)/0.00245m= 1.373*10^-11 F
But for the final calculation to find the charge I took Q= C*V = (1.373*10^-11 F)*-1923.25 V= -2.641*10^-8C So do I need to include the negative in that final calculation to get a negative charge or do I leave it out?