Answer
0.269 nm
Work Step by Step
Apply equation 25–10 with m = 2.
$$m\lambda=2dsin\phi$$
$$d= \frac{m \lambda}{2sin\phi}= \frac{(2)(0.0973nm)}{2(sin21.2^{\circ})}$$
$$d=0.269nm$$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.