Enough room that you can see them
Find out the measurements of the bed and then measure that in the room.
However much you find comfortable, it's entirely up to you.
about half a a humans normal room
2 Gigabyte can hold up to 500 songs. If you add pictures, then that takes up on a lot of space.
If you know the volume, you know how much stuff it can hold and how much space it takes up.
because they need room for the particles to move around
Light can fill a room without taking up physical space.
14 by 14 square foot will be plenty of space.
Yes, apps take up memory and space on your iPod.
Volume in geometry is how much space an object can hold/takes up. In sound, volume is how loud something is.
It depends on the size of the cage. They will take a bit of space but not so much that you will get annoyed with it. Maybe about half/a quarter of a room or so.