Question

Suppose that the light from the pinhole projects onto a screen 3.00 meters away. What is the radius r1 of the first dark ring on that screen? Notice that the angle from part a is small enough that sinθ≈tanθ.

Answer 1

16 mm

Explanation:

The next information is misssing: The first dark ring can be found at angle 0.305 degrees.

A rigth triangle is formed in wich one leg is the radius r1 of the first dark ring and the other leg is the distance between the screen and the laser (L), which is equal to 3 meters.

Using the relationship sinθ≈tanθ we get:

tanθ = r1/L

tan 0.305 = r1 / 3

r1 = tan(0.305°) * 3 m

r1 = 0.016 m = 16 mm