I read the *Transformer and Inductor Design Handbook* and I have some question would like to ask you guys.

1. Why are the EE or EC cores shown in Figure 1-30B the bested suited?
2. Why is only Figure 1-30B lg 1 while Figure (A), (C), (E) lg are 1/2?

[![enter image description here](https://i.stack.imgur.com/4Nb1Y.png)](https://i.stack.imgur.com/4Nb1Y.png)

[![enter image description here](https://i.stack.imgur.com/QRQ50.png)](https://i.stack.imgur.com/QRQ50.png)