A parallel-plate capacitor is constructed of two horizontal 17.2 cm-diameter circular plates. A 1.2g plastic bead, with a charge of -5.2nC is suspended between the two plates by the force of the electric field between them.

What is the charge on the positive (upper) plate?

Explanation:

Given:

diameter, d = 0.172 m which means radius, r = 0.086 m

mass of bead = 1.2 g

= 0.0012 kg

charge of bead = -5.2 nC

= -5.2 × 10^-9 C

E = Q/(p*A)

where,

E = electric field

= F/Q

= (0.012 × 9.8)/5.2 × 10^-9

= 2.26 × 10^7 N/C

p = permittivity constant

= 8.85 × 10^-12 C/(N*m^2)

A = area of capacitor.

= pi × r^2

= 0.093 m^2

Q = E*p*A

= 2.26 × 10^7 × 8.85 × 10^-12 × 0.093

= 1.86 × 10^-5 C

potential energy is directly proportional to height.

more height = more potential energy.

greatest increase in height = greatest increase in potential energy

where are the points with the greatest increase in height ?

has to be c-e or d-e .

are there answer choices to this question? this seems like a question where you have options to choose from.