A 17.0 g piece of Styrofoam carries a net charge of −7.00 μC and floats above the center of a large horizontal sheet of plastic that has a uniform charge density on its surface. What is the charge per unit area (in C/m2) on the plastic sheet? (Include the sign of the value in your answer.) Hint

Explanation:

Given that,

Mass of styrofoam =17g=0.017kg

Net charge is q =−7.00 μC

Electric field of a sheet is given as

E = σ / 2εo

σ= charge density

εo= permittivity of free space =8.85×10^-12

Also electric field is given as

E=F/q

The force acting on the body is its weight which is given as

F=mg,

Where g=9.81

F=0.017×9.81

F=0.16677N.

Therefore,

E=F/q

E=0.16677 /- 7×10^-6

E=-23824.29N/C

Then,

E = σ / 2εo

Then, σ = E × 2εo

σ=-23824.29×2×8.85×10^-12

σ= - 4.22×10^-7C/m²

σ= -42.2×10^-6 C/m²

σ= -42.2 μC/m²

The charge density is -42.2 μC/m²