Hwksolns8TAn2

# Hwksolns8TAn2 - Solutions for HW 8 Chapter 25 Conceptual...

This preview shows pages 1–3. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Solutions for HW 8 Chapter 25 Conceptual Questions 25.1. 1 θ decreases. As the crystal is compressed, the spacing d between the planes of atoms decreases. For the first order diffraction m =1. The Bragg condition is 2 cos m m d λ θ = so as d decreases, cos m θ must increase for the condition to be satisfied . But cos θ increases as θ decreases. Hence there will be a decrease in the angle of incidence. 25.2.   (a) a b c E E E because the energy per photon depends only on the frequency so / . E hf hc λ = = The smaller wavelengths correspond to higher frequencies. (b) c b a N N N because the powers are equal, there must be more photons when the energy per photon is less. 25.3. The energy of a photon is given by / . E hf hc λ = = Therefore the ratio of energies is, 2 2 1 1 1 1 / 1 / 2 2 E hc E hc λ λ λ λ = = = 25.5. Fast electrons will have a shorter wavelength leading to less diffraction spreading and better resolution. 25.7. Because 2 2 2 8 n h E n mL = we see that for a given n , n E is inversely proportional to 2 L . If L is doubled then n E is decreased by a factor of 4. So the new 19 1 1 10 J. E- = × 25.8. It is the same, or 20 1.0 10 J.- × 1 1 1 2 2 H He H 2 2 8 8(4 ) 2 h h E E E m L L m = = = Exercises and Problems 25.4. Model: The angles of incidence for which diffraction from parallel planes occurs satisfy the Bragg condition. Solve: The Bragg condition is 2 cos , m d m θ λ = where m = 1, 2 For first and second order diffraction, respectively ( 29 1 2 cos 1 d θ λ = ( 29 2 2 cos 2 d θ λ = Dividing these two equations, ( 29 ( 29 1 1 2 2 1 1 cos 2 cos 2cos cos 2cos68 41 cos θ θ θ θ-- = ⇒ = = ° = ° 25.7. Model: The angles corresponding to the various diffraction orders satisfy the Bragg condition. Solve: The Bragg condition is 2 cos m d m θ λ = , where m = 1, 2, 3, … gives the order of diffraction. The maximum possible value of m is the number of possible diffraction orders. The maximum value of cos θ m is 1. Thus, we tend to find the value of m for the limiting value of cos θ m....
View Full Document

{[ snackBarMessage ]}

### Page1 / 6

Hwksolns8TAn2 - Solutions for HW 8 Chapter 25 Conceptual...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online