This equation suggests that a graph of threshold stimulus strength versus stimulus duration should show a decay toward zero as stimulus duration is increased, so the stimulus strength required to reach threshold is predicted to increase during more protracted stimulation. The strength-duration curve for a typical nerve membrane is slightly skewed from the predicted graph, in that the curve flattens out in response to repetitive stimulation reaching an asymptote representing rheobase. When the duration of a stimulus is prolonged, charge transfer and membrane potential rise exponentially to a plateau (instead of increasing linearly with time). When rheobase exceeds the strength of the stimulus, stimulation fails to generate action potentials (even with large values of t); thus if the stimulus is too small, the membrane potential never reaches threshold. The disparity between the shape of the strength-duration curve predicted by Weiss's equation and the one actually observed in neural membranes can be attributed to leakage of charge that occurs under physiological conditions, a feature of the electrical resistance of the membrane. Weiss' equation predicts the relationship between stimulus strength and duration for an ideal capacitor with no leakage resistance.