Intensity for a Double Slit
To find the overall intensity of the double-slit pattern, simply multiply the double-source intensity by the single-slit intensity:
| Iav |
= |
Imax cos2 |
( |
| pd sin(q)
|  |
| l
|
|
) |
[ |
| sin [pa sin(q) / l]
| |
| pa sin(q) / l
|
|
] |
2 |
When we use the double-source equation to find locations of bright spots, we find that at some places where we expect to see bright spots we see no light. This is known as a missing order, and it happens because at that location there's a zero in the diffraction pattern.
What is the ratio of d/a that produces the pattern shown in the simulation above? The answer is an integer. Use that key on your transmitter to enter your response.