Question
for face centered unit cell, r=6
find edge in terms of r, face diagonal in terms of r, body diagonal in terms of r,
edge=squareroot(8)r
face=4r
but i don't know how to find body diagonal
find edge in terms of r, face diagonal in terms of r, body diagonal in terms of r,
edge=squareroot(8)r
face=4r
but i don't know how to find body diagonal
Answers
DrBob222
Isn't the face diagonal
4r = a*2<sup>1/2</sup>
The body diagonal is a*3<sup>1/2</sup> .
The triangle has sides of a (the upright line on the left side of the unit cell), the diagonal (along the floor of the unit cell which we know is a*2<sup>1/2</sup> so the body diagonal is the hypotenuse of that triangle. So d<sub>b</sub><sup>2</sup> = a<sup>2</sup> + (a*2<sup>1/2</sup>)<sup>2</sup>
I hope this turns out right.
4r = a*2<sup>1/2</sup>
The body diagonal is a*3<sup>1/2</sup> .
The triangle has sides of a (the upright line on the left side of the unit cell), the diagonal (along the floor of the unit cell which we know is a*2<sup>1/2</sup> so the body diagonal is the hypotenuse of that triangle. So d<sub>b</sub><sup>2</sup> = a<sup>2</sup> + (a*2<sup>1/2</sup>)<sup>2</sup>
I hope this turns out right.
DrBob222
It looks ok to me. You solve, of course, for d<sub>b</sub><sup>2</sup> then take the square root of it. That should be the d<sub>b</sub> = a*3<sup>1/2</sup>
student
for body diagonal. take face diagonal and square it and take edge diagonal and square it. add those 2 together than take the SQUARE ROOT of it. Answer. so its basically the a^2+b^2=c^2 equation.