Room A3 "Reversal"

This time, the entry portal is fixed and the exit is free.

The order you do things will be particularly important.

Try to get the closest door open first.

There's one receiver by the entry portal - how might you hit it?

Entry portals can also be exit portals - you need a particle to emerge from the bottom of the first portal.

Make use of the two arrows behind the door along with the moveable left-arrow to send a particle back through the portal.

The emitter facing upwards hasn't been used yet.

You'll need the left-arrow to make use of it.