Ri, as represented in fig.7 . The past separated by a broken line.
If the source current i equals
I=du df/dt
The generated charged Q according to the equivalent circuit in fig 7. equals.
Q= idt = dij df= dij F
In(7) the influence of the leakage resistant Ri is omiited whose time constant T calculated from the magnitude of resistant Ri and capacity Ci will be smaller than the time t needed to charege the force acting on the sample ; consindering the real preparation , it is the time of lifting the loaing level from the sample . Therefore t