Answer
a. $y_J=2.48\times10^{-4}m$, $y_L=2.05\times10^{-4}m$.
b. $\Delta y = 0.043mm$.
Work Step by Step
a. Apply the formula $y=m(\frac{\lambda}{2})$.
First, Jan.
$$y_J=818(\frac{606\times10^{-9}m}{2})=2.48\times10^{-4}m$$
Next, Linda.
$$y_L=818(\frac{502\times10^{-9}m}{2})=2.05\times10^{-4}m$$
b. The fringes moved in opposite directions. Jan and Linda moved the mirror in opposite directions.
$$\Delta y = 0.248mm-0.205mm=0.043mm$$
