ELI5 how do hand scanners work with people who have missing fingers

ELI5: How does gravitons work? (If they exist..)

ELI5: Why is crack so much cheaper than cocaine when cocaine is just cooked crack?

ELI5; the main cycles in biology.

ELI5: why does mouthwash sting?

ELI5 Why purpose do washers serve when using it with a nut to tighten screws.

ELI5 in Clue 1985, explain catching other actors' reaction shots to Kahn's improvised "flames" speech, while filming using 1 camera!