Answer
$24.0mm$
Work Step by Step
First, we use a trig ratio to relate the angle, the distance to the minima, y, and the length to the screen, L.
$\sin \theta =y/L$
Now we can use the above relationship and the give values in equation (36-3) to solve for the distance to the minima, y,
$\alpha \sin \theta = \Delta m \lambda $ where $m=1,2,3,....$ (minima)
$\alpha (\Delta y/L) = \Delta m \lambda $
$\Delta y = \Delta m \lambda L / \alpha $
$\Delta y = (10-(-10)) *632.8*10^{-9}m* 2.60m / (1.37*10^{-3}m)$
$\Delta y = 24.0*10^{-3}m$
$\Delta y = 24.0*mm$
