{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

homework 5

# Principles of Quantum Mechanics

This preview shows pages 1–2. Sign up to view the full content.

Electromagnetic Fields Homework (Chapter 7) Name: Deng xiaolong (a ) ID Number: 200982009 7-5 Find the energy of the charge distribution of Exercise 5-17 by using (7-8). Answer: as we know (7-8) is 1 ( ) ( ) 2 e S U r r da σ φ = v v and the potential of Exercise 5-17 is 2 2 1/2 0 ( ) [( ) ] 2 z z a z σ φ ε = + - We just need calculate the energy produced in the circular disc. So we need only consider the potential at 0 z = , i.e., 0 (0) 2 a σ φ ε = We also have this expression: da rdrd θ = , where 0 ' 2 θ π and 0 ' r a S Therefore: 2 0 0 0 1 1 ( ) ( ) 2 2 2 a e S a U r r da rdrd π σ σ φ σ θ ε = = �� v v Finally, we can get the result: 2 2 2 3 0 0 1 2 2 2 2 4 e a a a U σ πσ π ε ε =↓∞ = That means the energy of the charge distribution of Exercise 5-17 is: 2 3 0 4 e a U πσ ε = . 7-11 The coaxial cylindrical conductors of Figure 6-12 are used as a capacitor with charges per unit length l q and l q - . Find the energy of a length L of this system by using (7-28) and thus show that the capacitance is (6-45).

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.

{[ snackBarMessage ]}

### Page1 / 2

homework 5 - Electromagnetic Fields Homework(Chapter 7 Name...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online