Answer:
To find the net charge on the sphere using electric flux, we can use the formula:
Φ = Q/ε0
Where Φ is the electric flux, Q is the charge, and ε0 is the permittivity of free space.
Given that the electric field 20 cm from the center of the sphere is N/C and points radially inwards, we can use the formula for electric field due to a charged sphere to find the charge on the sphere:
E = kQ/r^2
Where E is the electric field, k is Coulomb's constant, Q is the charge, and r is the distance from the center of the sphere.
Substituting the given values, we get:
20 = (1/4πε0)(Q)/(0.2)^2
Solving for Q, we get:
Q = (20)(0.2)^2(4πε0)
Q = 0.64πε0 C
Now, substituting this value of Q in the formula for electric flux, we get: Φ = Q/ε0 = (0.64πε0)/(ε0) = 0.64π C
Therefore, the net charge on the sphere is 0.64π C.