# Electromagnetism problem

1. Sep 28, 2006

### drcrabs

How does one calculate the reflection coefficient for light at an air to silver interface at optical frequencies ($$\omega = {4 *10^{15} s^{-1}}$$)
given

$$\mu_{I} = \mu_{T} = \mu_{0} , \sigma = {6 * 10^7 mhom^{-1}}$$

Last edited: Sep 28, 2006
2. Sep 29, 2006

### Meir Achuz

The reflection is close to 100% for silver.
the reflected intensity is I_r=I_0-I_absorbed.
$I_{absorbed}=\sqrt{\omega/8\pi\sigma}I_0$ in Gaussian units.

3. Sep 29, 2006

### drcrabs

Would this work?

Knowing the frequency means we can find the wavelength clearly, which has units metres, clearly. When combined with $$\sigma = {6 * 10^7 mhom^{-1}}$$ to get the impedance of the silver. Then taking the ratio with the impedance of free space and assuming normal incidence

$$r =\frac{1 - \beta}{1 + \beta}$$

where $$\beta = \frac{\eta_0}{\eta_s}$$

Would this work?

Last edited: Sep 29, 2006
4. Sep 30, 2006

### Meir Achuz

How would you calculate \eta?

5. Sep 30, 2006

### drcrabs

eta_s is the impeance of silver. As indicated previously a value with ohm units can be achieved by combining wavelength with the value of conductivity. What im asking is, is this a valid statement?

6. Oct 1, 2006

### Meir Achuz

No. Units are not a calculation.

7. Oct 1, 2006

### luckysahi

i want to know about the motion of the stelites totely

8. Oct 1, 2006

### luckysahi

basic defination of electromagnatic physics

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