Auto Update Person or Group Column to SharePoint List

Hello,

I have a two lookup columns i.e.

1. Business

2. Approver EID

3. Person or Group

Into Business I have 3 choice i.e. Elec, Aero and Hyd

Say for example : if a user selects Elec, then we see My EID i.e. E123456 in the Approver EID column

Similarly, if user selects Aero, then we see Rick as the name in the Approver EID column.

So what I'm trying to achieve is: in Person or Group column, Email address should automatically get populated against EID mentioned in Approver EID column.

For E.g.