Question

why are we adding 3 ohm and 2ohm when key is open plz explain urgent​

Answer 1

Answer:

They are added when the key is closed. Take a look

For such questions, go along the wire. since the key is open, no current flows through the wire containing 2ohm and 3ohm. Hence, we do not include their resistance and vice versa.

Answer 2

Answer:

we are not adding it.

we are just neglecting it because no current is flowing through it