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## Homework Statement

A small sphere with charge 2.4 micro coulombs is suspended from a thread between 2 charged plates. The plates have a voltage of 62 and the distance between the plates is 3.1 cm. The sphere hangs at 18 degrees to the vertical.

## Homework Equations

E = V/r

FE = Eq

Fnetx = FE - FT

Fnety = FTy - Fg

## The Attempt at a Solution

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E = 62V/0.031m = 2000 N/C

FE = Eq = (2000 N/C)(2.3 x 10^-6 C)

FTx = FE = 4.6 x 10^-3 N

FTy = FE * tan18 degrees

= 4.6 x 10^-3 N * tan18

= 1.5 x 10^-3 N

Fg = mg

1.5 x 10^-3 N = m(9.8 m/s^2)

m = 1.5 x 10^-4 kg