The ceiling of your lecture hall is probably covered with acoustic tile, which has

The ceiling of your lecture hall is probably covered with acoustic tile, which has small holes separated by about 6.9 mm. using light with a wavelength of 579 nm, how far could you be from this tile and still resolve these holes? the diameter of your eye is about 5 mm.

( )m

could you resolve these holes better with red light or with violet light? (you have only 1 try.)

1. violet.

2. red