A beam of red light has twice the intensity as a second bean of the same color

AI Thread Summary
A beam of red light with twice the intensity compared to another beam of the same color requires calculating the ratio of their amplitudes. The relationship between intensity and amplitude is given by the equation intensity ∝ (amplitude)^2. By expressing the intensities as I_1 = kA_1^2 and I_2 = kA_2^2, the ratio of intensities can be used to derive the amplitude ratio. The correct amplitude ratio is not 1:4, as initially suggested, but must be calculated based on the intensity relationship. The discussion emphasizes the importance of correctly applying the intensity-amplitude relationship to find the solution.
looi76
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Homework Statement


A beam of red light has twice the intensity as a second bean of the same color. Calculate the ratio of the amplitude of wave.

Homework Equations


intensity \propto (amplitude)^2

The Attempt at a Solution


1^{st} \mbox{ beam} = 2I
2^{nd} \mbox{ beam} = I

I don't know if this step is correct and I don't know what to do next?!
 
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looi76 said:

Homework Equations


intensity \propto (amplitude)^2

The Attempt at a Solution


1^{st} \mbox{ beam} = 2I
2^{nd} \mbox{ beam} = I


I_1=2 I_2

\frac{I_1}{I_2}=2

What can you do to the above relation (given your relevant equation) to convert it to a ratio of amplitudes?

Regards,

Bill
 
intensity \propto (amplitude)^2

So, it will be 1:4 ?
 
No, start off by expressing both intensities I = kA^2. Then compare the ratio of each amplitude to the other.
 
looi76 said:
intensity \propto (amplitude)^2

So, it will be 1:4 ?

No. Try what Defennder suggested to see why.

Regards,

Bill
 

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