$ 1 % - - - $ % Figure 1: Structure of a vacuum tube diode. The filament may be bare, or more comm nly (as shown here), embedded within and insulated from an encl enclosi osin n catho cathode de
Figure 5: Current-voltage characteristic of a Zener diode with a breakdown voltage of 17 v olt. Notice the change of voltage scale between the forwar d biased (positive) direction and the reverse biased (negative) direction.
