# Find the surface charge density

#### mr_coffee

Helllo everyone i'm stuck. A sphereical metal satelliete 1.3m in diameter accumulates 2.4x10^-6 C of charge in one orbital revolution. Find the resulting surface charge density. This is a simple plug in chug problem i think....I know the charge and radius but i can't finda formula that works. The closest one i found was: E = $$\delta$$/Eo; Any suggestions?

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#### Doc Al

Mentor
You have the charge. All you need is the surface area. Look up the formula for the surface area of a sphere.

#### mr_coffee

ohhh so charge here doesn't mean q enclosed, it means surface charge density? So i could use E = $$\delta$$/(2piEor)

#### Doc Al

Mentor
mr_coffee said:
ohhh so charge here doesn't mean q enclosed, it means surface charge density?
Right. The problem (as you gave it) states: "Find the resulting surface charge density."

And the most direct way to calculate surface charge density is by its definition: [surface charge]/[surface area]. So... what's the surface area of a sphere?

#### mr_coffee

Oh i think you misunderstood when i said, "ohhh so charge here doesn't mean q enclosed, it means surface charge density? " I was talking about, it said: "...accumulates 2.4x10^-6 C of charge in one orbital revolution." <---that charge is q not $$\delta$$ right? The surface are of a sphere is 4PIr^2. E = $$\delta$$/(4PIr^2Eo) like that?

#### mr_coffee

ahhh n/m i'm retarded, i didn't even read ur post cleary, thanks i got it with ur suggestion!!

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