You Do Need power plug adapter while traveling from Cambodia to Brazil.

Here is Why You Need An Adapter

The outlet and plug type used in Brazil are C and N and in Cambodia are A, C and G. This is how they look like.

Cambodia

In Cambodia, outlets of type A, C and G are in use.

Type A

Type C

Type G

Brazil

In Brazil, outlets of type C and N are in use.

Type C

Type N