You Do Need power plug adapter while traveling from Antigua and Barbuda to Sri Lanka.

Here is Why You Need An Adapter

The outlet and plug type used in Sri Lanka is G and in Antigua and Barbuda are A and B. This is how they look like.

Antigua and Barbuda

In Antigua and Barbuda, outlets of type A and B are in use.

Type A

Type B

Sri Lanka

In Sri Lanka, outlets of type G are in use.

Type G