By looking at the Josephson equations, we see that a positive constant, then just increases linearly without bound.
Therefore, from the first equation: .
Wikipedia mentions that this frequency is , so it is very very high, so we are not able to view individual points of the sine curve separately with our instruments.
An I-V curve can also be seen at: Figure 4. "Electron microscope image of a Josephson junction its I-V curve".