Find the power of a convex lens if the image formed is at a distance of 16 cm from the lens when the object is placed on the other side of the lens at 20 cm from the optical centre?
Use SAVE when you want to update the lastly preserved or to revise an existing document or file with the latest content.
Whereas
Use SAVE AS when you are creating a new document/file or an existing document/file to a new location. This will keep the original document untouched in its original format and create a new document with a new name.