Here's why you need an adapter
The outlets and plugs used in Sri Lanka are D & G. Take a look at the pictures below to see what each plug and socket type looks like.
Voltage and frequency Afghanistan vs Sri Lanka
All outlets in Afghanistan provide a standard voltage of 220V with a frequency of 50Hz.Voltage: 220V Frequency: 50Hz
All outlets in Sri Lanka provide a standard voltage of 230V with a frequency of 50Hz.Voltage: 230V Frequency: 50Hz