1. Diffraction is a type of interference that occurs when light waves
   1. are emitted by a moving source
   2. pass through or by an obstacle
   3. have an excess of energy
2. Diffraction from a single slit produces a pattern of bright spots which
   1. are equal in intensity
   2. fade rapidly away from center
   3. grow brighter away from center
3. If red and blue light pass through the same slit in a mask, the pattern of red spots will
   1. have wider spacing than the blue spots
   2. have same spacing as the blue spots
   3. have narrower spacing than the blue spots