Asmall negatively charged sphere with a mass of 5.4*10^-5 is suspended between two parallel plates. the potential difference is 360v to hold the sphere stationary. what is the sphere's charge?

Here, Fe = Fg
q.E = m.g
We have: E = 360 V
m = 5.4 × 10⁻⁵
g = 9.8 m/s²   [ constant value for earth system ]

Substitute their values into the expression:
q (360) = 5.4 × 10⁻⁵ × 9.8
q = 52.92 × 10⁻⁵ / 360
q = -1.47 × 10⁻⁶  [ negative sign represents the nature of charge ] 

So, Your Final answer would be 1.47 × 10⁻⁶

Hope this helps!