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# Isaac Physics - Combining Waves (help needed)

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1. Hi, there is a question on Isaac Physics about intensity and amplitude which should be quite straightforward - https://isaacphysics.org/questions/c...a-e536644b3e2a.

'Two coherent waves of intensities I and 2I meet in phase at a point. For these waves I∝A^2, where A is the amplitude. What multiple of II is the intensity of the resulting wave at that point? Give your answer to 2 significant figures.'

I keep putting 5^1/2 which is 2.2 to 2 sig figs, what am I doing wrong?
2. Convert the intensities to an amplitude, perhaps draw a sketch as well. The resultant wave has an amplitude equal to the sum of the amplitudes of the incident waves, you have to convert between intensity and amplitude twice I believe.
3. (Original post by JN17)
Convert the intensities to an amplitude, perhaps draw a sketch as well. The resultant wave has an amplitude equal to the sum of the amplitudes of the incident waves, you have to convert between intensity and amplitude twice I believe.
Did you get the right answer?
4. Yes, just be careful with what you have to square or root.

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