Capacitance and maximum charge HELP

AI Thread Summary
The discussion focuses on calculating the capacitance of a parallel-plate capacitor modeled as a cloud and the ground, with the cloud at 620 meters altitude and a surface area of 0.16 km². The formula used is C=E0 A/D, where E0 is the permittivity of free space. Participants are seeking assistance with the calculations, as initial attempts did not yield the correct capacitance in nanofarads (nF) or the maximum charge before lightning occurs. The thread emphasizes the need for accurate conversions and calculations to arrive at the final answers. Accurate capacitance and charge values are crucial for understanding the lightning phenomenon modeled in this scenario.
seant
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As a crude model for lightning, consider the ground to be one plate of a parallel-plate capacitor and a cloud at an altitude of 620 m to be the other plate. Assume the surface area of the cloud to be the same as the area of a square that is 0.40 km on a side.
(a) What is the capacitance of this capacitor?
nF
(b) How much charge can the cloud hold before the dielectric strength of the air is exceeded and a spark (lightning) results?
C

I used C=E0 A/D (8.85*10^-12 C^2/N*m^2)(.16km^2/620m) and conversions also, but to no avail can someone please help
 
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Hi seant,

seant said:
As a crude model for lightning, consider the ground to be one plate of a parallel-plate capacitor and a cloud at an altitude of 620 m to be the other plate. Assume the surface area of the cloud to be the same as the area of a square that is 0.40 km on a side.
(a) What is the capacitance of this capacitor?
nF
(b) How much charge can the cloud hold before the dielectric strength of the air is exceeded and a spark (lightning) results?
C

I used C=E0 A/D (8.85*10^-12 C^2/N*m^2)(.16km^2/620m) and conversions also, but to no avail can someone please help

What number did you get as your final answer, in nF?
 

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