What is the capacitance of the two metal spheres

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SUMMARY

The capacitance of two metal spheres with charges of 20nC and -20nC, experiencing a voltage change of 100V, can be calculated using the formula C=Q/(ΔV). In this case, the charge Q is taken as 20nC, leading to a capacitance of 2E-8 F or 20nF. The discussion clarifies that when two charges are provided, the positive charge should be used for calculations, as capacitance is inherently symmetric in such scenarios.

PREREQUISITES
  • Understanding of capacitance and its formula C=Q/(ΔV)
  • Knowledge of electric charge units, specifically nanocoulombs (nC)
  • Familiarity with voltage concepts and their role in capacitance
  • Basic principles of electrostatics and charge interactions
NEXT STEPS
  • Study the derivation and applications of the capacitance formula C=Q/(ΔV)
  • Explore the concept of electric field and its relation to capacitance
  • Investigate the behavior of capacitors in series and parallel configurations
  • Learn about the effects of dielectric materials on capacitance
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Students in physics or electrical engineering, educators teaching electrostatics, and anyone interested in understanding the principles of capacitance and charge interactions.

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Homework Statement


What is the capacitance of the two metal spheres shown in the figure ?

sphere one has 20nC of charge and the other has -20nC of charge. The change in voltage is 100V

Homework Equations


C=Q/(change in V)


The Attempt at a Solution


My question is how do yo determine what charge to put in for Q?
 
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hover said:

Homework Statement


What is the capacitance of the two metal spheres shown in the figure ?

sphere one has 20nC of charge and the other has -20nC of charge. The change in voltage is 100V

Homework Equations


C=Q/(change in V)

The Attempt at a Solution


My question is how do yo determine what charge to put in for Q?

It's given.
 


xcvxcvvc said:
It's given.

but the thing is how would I know to use 20nC or -20nC? What if you had 2 charges that were something like -30nC and 20nC? How do you know what Q to choose?
 


hover said:
but the thing is how would I know to use 20nC or -20nC? What if you had 2 charges that were something like -30nC and 20nC? How do you know what Q to choose?

you will never be given a problem like that. the charge when dealing with capacitance will be symmetric if two values are given or it will be singular(where such an ambiguity is impossible)
 


So i assume then that the answer here is just 2E-8/100 then
 


hover said:
So i assume then that the answer here is just 2E-8/100 then

assumed correct.
 


xcvxcvvc said:
assumed correct.

Correct

thanks
 

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