I need help with this physics question. Please. Thanks in advance.

Question

For a disk of radius R = 17 cm and Q = 5 ✕ 10-6 C, calculate the electric field 1 cm from the center of the disk using all three formulas below. Note: ε0 = 8.85e-12 C2/(N·M2).

I got c to be 3.114e6 N/C. I don't know how to do a and b because of the z in the equation.

 

(a) Most accurate approximation:
E = Q/A/2ε0 * ( 1 − z/((R2 + z2)^1/2)

(b) Less accurate approximation:
E = Q/A/2ε0 * (1 − z/R)

(c) Least accurate approximation:
E = Q/A2ε0

Answer 1

I confirm your answer for (c). For (a) and (b), assume z is the perpendicular distance from the center of the disk, along the axis of the disk. In this problem, z is given to you.

z = 1 cm = 10^-2 m

You should be able to take it from here.