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wbluem88

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## Homework Statement

(a) A charge of -345e is uniformly distributed along a circular arc of radius 4.00 cm, which subtends an angle of 41°. What is the linear charge density along the arc?

(b) A charge of -345e is uniformly distributed over one face of a circular disk of radius 1.90 cm. What is the surface charge density over that face?

(c) A charge of -345e is uniformly distributed over the surface of a sphere of radius 1.90 cm. What is the surface charge density over that surface?

(d) A charge of -345e is uniformly spread through the volume of a sphere of radius 1.90 cm. What is the volume charge density in that sphere?

## Homework Equations

## The Attempt at a Solution

OK so this should be really simple right??

Part a)

CHARGE / DISTANCE

(-345 * 1.602 * 10^-19)/((41/360)*2*pi*.04) = -1.9309*10^-15 C/m

Part b)

CHARGE / AREA

(-345 * 1.602 * 10^-19)/(pi*.019^2) = -4.8733*10^-14 C/m^2

part c)

CHARGE / AREA

(-345 * 1.602 * 10^-19)/(4*pi*.019^2) = -1.2183*10^-14 C/m^2

part d)

CHARGE / VOLUME

(-345 * 1.602 * 10^-19)/((4/3)*pi*.019^3) = -1.9236*10^-12 C/m^3

According to my WebAssign homework, all these are wrong. What am I doing?