You Do Need power plug adapter while traveling from Dominican Republic to Sri Lanka.

Here is Why You Need An Adapter

The outlet and plug type used in Sri Lanka is G and in Dominican Republic are A, B and C. This is how they look like.

Dominican Republic

In Dominican Republic, outlets of type A, B and C are in use.

Type A

Type B

Type C

Sri Lanka

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

Type G