The charge density of a uniformly charged disk 0.420 m in diameter is 2.92 ✕ 10-2 C/m2. What is the magnitude of the electric field along the disk's axis at the following distances from its center?

E = { (Charge Density/2e0) * (1 - [z / (sqrt (z^2 - R^2)) ]}

R is radius = Diameter/2 = 0.210m.

At z = 0.2m,

Put z = 0.2m, and charge density = 2.92 x 10^-2C/m2, and constant value e0 in the equation,

E can be calculated at distance 0.2m away from the centre of the disk.

Put z = 0.3m and all other values in the equation,

E can be calculated at distance 0.3m away from the centre of the disk