An investigator conducts two trials of a double-slit interference experiment using different configurations. The table below details the wavelength of light used, the slit separation, the distance from the double-slit to the screen, and the resulting fringe width (separation between adjacent bright fringes).
| Trial | Wavelength | Slit separation | Screen distance | Fringe width |
|---|---|---|---|---|
| 1 | λ\lambdaλ | sss | DDD | 3.5 mm |
| 2 | 1.2λ1.2\lambda1.2λ | 1.5s | 0.75D0.75D0.75D | w2w_2w2 |
What is the fringe width w2 w_2\,w2 observed in Trial 2?
2.1 mm2.1\text{ mm}2.1 mm
3.2 mm3.2\text{ mm}3.2 mm
4.7 mm4.7\text{ mm}4.7 mm
8.4 mm8.4\text{ mm}8.4 mm