# confused about diode polarity vs circuit polarity

I know the anode has a + sign and cathode has negative sign. But are these signs reversed depending on how the diode is connected with the circuit?

In the above pic, in fig 4.2b, why isnt the - sign on the top and + sign on the bottom of the diode, since the cathode is on the top side? Also, what does -v indicate in fig 4.2b?

• Note that Fig 4.2 (b) violates every known datasheet Absolute Maximum for Vr ( if it were an LED) Although we refer to Zeners as the reverse Voltage -V they are often assumed positive as if you understand it is an absolute value as a component – Sunnyskyguy EE75 Sep 8 '18 at 0:25