Correct Answer - `(2 lambda sqrt(R^(2) - d^(2)))/(epsilon_(0))`
For Rltd, the flux will be zero. It is because there is no charge
line inside the sphere figure. For Rltd, the length inside the sphere is `2(sqrt(R^2-d^2))`. So the charge inside is `2lambda sqrt(R^2-d^2)`.
Thus `phi = (2lambdasqrt(R^2-d^2))/epsilon_0`