Question 22N.2.HL.TZ0.7c
| Date | November 2022 | Marks available | [Maximum mark: 3] | Reference code | 22N.2.HL.TZ0.7c |
| Level | HL | Paper | 2 | Time zone | TZ0 |
| Command term | Comment | Question number | c | Adapted from | N/A |
A beam of coherent monochromatic light is incident normally on a single rectangular slit. The diffraction pattern is observed on a screen.
O is the point on the screen directly opposite the slit. P and Q are the first minima on either side of the central fringe of the diffraction pattern.
The light source actually emits two wavelengths of light. The average wavelength is 590 nm and the difference between the two wavelengths is 0.60 nm.
A student attempts to resolve the wavelengths using a diffraction grating with 750 lines per mm. The incident beam is 2.0 mm wide.
Comment on whether this diffraction grating can resolve the wavelengths in the first-order spectrum.
[3]
ALTERNATIVE 1
number of illuminated slits ✓
smallest resolvable difference «» «nm» ✓
hence the lines can be resolved ✓
ALTERNATIVE 2
number of illuminated slits ✓
✓
greater than hence lines can be resolved ✓
Allow ECF from MP2.
Many answers showed confusion about the meaning of the equation in the data booklet. There were some wrong conclusions that compared the two numbers, and not being equal, concluded that the lines could not be resolved. Strongest candidates scored full marks easily.
