A beam of green light falls normally on a diffraction grating. A number of bright spots appear on a screen on the far side of the grating, as shown. Which pair of changes could produce bright spots at exactly the same angles as before?
- AUse blue light and increase the distance between the grating and the screen.
- BUse blue light and increase the number of lines per unit length in the grating.
- CUse red light and increase the distance between the grating and the screen.
- DUse red light and increase the number of lines per unit length in the grating.