Two students, Francis and Dalton, make single-slit slides in ...

[Mr. Wonderful]

Two students, Francis and Dalton, make single-slit slides in order to see the Fraunhofer diffraction pattern themselves. Francis makes a slide with a slit of size a. Dalton's hand slips when she's making the slit, and winds up with a slit twice as wide as her classmate's. They both use the same monochromatic light filtered by their respective slides to project a diffraction pattern on screen a distance L away. The distance between fringes on Francis' will be
  1.two times greater than that on Dalton's.
  2.the same as the spacing on Dalton's.
  3.half that of Dalton's.
  4.some size smaller than Dalton's.

Question 2

A student is studying a Fraunhofer diffraction pattern. She measures the distance between the center of one dark fringe and the center of the next dark fringe some small distance from the central maximum, and finds them to be 4 mm apart. To get a high grade on her lab, she should predict that the distance between the dark fringes on either side of the central maximum will be
  1.4 mm.
  2.2 mm.
  3.8 mm.
  4.not enough information to predict.

[Jbrasil]

Answer to Question 1

1

Answer to Question 2

3