How to split a column using a delimiter while still retaining its value

I have a dataset as shown below:

Cola                 colb
1.2/1.4/1.5/1.6      A
3.3/5.6              B

I want to have one column

COlA Colb
1.2   A
1.4   A
1.5   A
1.6   A
3.3   B
5.6   B

How do I do this in python