L lily New member Oct 7, 2011 #1 A lens of known focal length 200 mm is placed 32 cm from a lamp with a crosshair on its surface. Where should a screen be placed in order to show a focused image of the crosshairs projected by the lens?
A lens of known focal length 200 mm is placed 32 cm from a lamp with a crosshair on its surface. Where should a screen be placed in order to show a focused image of the crosshairs projected by the lens?
