Find out the value of phase for values of dc attenuation

Question

For the electrode amplifier interface model outlined within given figure, illustrate that the maximum phase shift introduced within a signal at the amplifier interface happens at a frequency equivalent to the geometric mean of the pole and zero frequencies as √(ω_p ω_z). 

Find out the value of given phase for values of dc attenuation of α = 0.5 and 0.02.