Science Buddies: "Ask an Expert"

I don't understand why are the intensities of the two lights become the same when the spot disappears. I know that is probably dump but I can't find an answer for days and it is very urgent to know why so please help. Also somone told me that it is because the light (radiation) pressure from both the lamps is the same when the spot disappears but I can't find anything related between the two things and I am not sure if it is true.

Hello,

Can you share a link to the project guide you are referencing?

Thanks,

Audrey