| Date | May 2014 | Marks available | 1 | Reference code | 14M.1.HL.TZ1.18 |
| Level | Higher level | Paper | Paper 1 | Time zone | Time zone 1 |
| Command term | Question number | 18 | Adapted from | N/A |
Question
Monochromatic coherent light is incident on a narrow rectangular slit. The diffracted light is observed on a distant screen. The graph below shows how the intensity of the light varies with position on the screen.
The width of the slit is reduced.
Which graph shows how the intensity of light observed varies with position on the screen? The original diffraction pattern is shown with a dotted line.
Markscheme
D
Examiners report
70% of the candidates assumed the peak intensity does not change and opted for either A or B. But if the slit width is reduced then the energy transmitted (and hence peak intensity) will be reduced.
