You Do Need power plug adapter while traveling from Myanmar (Burma) to Sri Lanka.

Here is Why You Need An Adapter

The outlet and plug type used in Sri Lanka is G and in Myanmar (Burma) are A, C, D, G and I. This is how they look like.

Myanmar (Burma)

In Myanmar (Burma), outlets of type A, C, D, G and I are in use.

Type A

Type C

Type D

Type G

Type I

Sri Lanka

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

Type G