- #1

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## Homework Statement

Could anyone help me to explain how the intensity of the double Slit pattern works because i'm looking at the formula and i'm really confused...

## Homework Equations

I=4Icos^2(phi/2)

A=2Ecos(phi/2)

- Thread starter lha08
- Start date

- #1

- 164

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Could anyone help me to explain how the intensity of the double Slit pattern works because i'm looking at the formula and i'm really confused...

I=4Icos^2(phi/2)

A=2Ecos(phi/2)

- #2

dx

Homework Helper

Gold Member

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What specifically do you want explained? The formula is easy to derive geometrically using the phasor diagram. Or you can do it algebraically: since only the phase difference matters, let the complex amplitude from slit one be just A (a real number). Then the complex amplitude from slit two will be Ae^{iφ}. The sum is therefore A(1 + e^{iφ}) = A(1 + cosφ + isinφ), and the magnitude squared is A²(1 + cos²φ + 2cosφ + sin²φ) = A²(2 + 2cosφ) = 2A²(2cos²(φ/2)) = 4A²cos²(φ/2).

Last edited:

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