DP Physics (last assessment 2024)
Question 18M.2.SL.TZ1.3a.i
| Date | May 2018 | Marks available | [Maximum mark: 3] | Reference code | 18M.2.SL.TZ1.3a.i |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Explain | Question number | a.i | Adapted from | N/A |
a.i.
[Maximum mark: 3]
18M.2.SL.TZ1.3a.i
A beam of coherent monochromatic light from a distant galaxy is used in an optics experiment on Earth.
The beam is incident normally on a double slit. The distance between the slits is 0.300 mm. A screen is at a distance D from the slits. The diffraction angle θ is labelled.
(a.i)
A series of dark and bright fringes appears on the screen. Explain how a dark fringe is formed.
[3]
Markscheme
superposition of light from each slit / interference of light from both slits
with path/phase difference of any half-odd multiple of wavelength/any odd multiple of (in words or symbols)
producing destructive interference
Ignore any reference to crests and troughs.
[3 marks]
