Answer:
0.7071D
Explanation:
Electric field strength is given as:
E = kq/r²
Where k = Coulumbs constant
q = charge
r = distance
When r = D, E = 1000 N/C
=> 1000 = kq/D²
=> kq = 1000D² ______ (1)
When E = 2000 N/C,
2000 = kq/r²
kq = 2000r² ____________ (2)
Since k is a constant and q is the same, equate (1) & (2):
2000r² = 1000D²
=> r² = 1000/2000 D²
r² = 0.5D²
=> r = 0.7071D