A-LevelPhysicsSuperposition9702/12 · Feb/Mar 2021 · Q291 Mark
A beam of red laser light of wavelength 633 nm is incident normally on a diffraction grating with 600 lines per mm. [Figure 29.1] The beam of red light is now replaced by a beam of blue laser light of wavelength 445 nm. A replacement diffraction grating is used so that the first-order maximum of the blue light appears at the same position on the screen as the first-order maximum of the red light from the original laser. How many lines per mm are there in the replacement diffraction grating?
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
A420 mm⁻¹
B470 mm⁻¹
C600 mm⁻¹
D850 mm⁻¹
✓ Correct answer
D: 850 mm⁻¹
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