In a Millikan type experiment, two horizontal plates are $3\mathrm{.}6$ cm apart. A latex sphere of mass $1\mathrm{.}8{10}^{-14}kg$ remains stationary when the potential difference between the plates is $920$ V $,$ with the upper plate positive.

$14$A

a$.$ Is the sphere charged negatively or positively?

b$.$ What is the magnitude of the electric field intensity between the plates?

c$.$ Calculate the magnitude of the charge on the latex sphere.

d$.$ How many excess or deficit electrons does the sphere have?