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# Unit 2 mcq q watch

1. Pls help! I know that Intensity is directly proportional to Amplitude^2 but I don't understand why the answer here is D

2. (Original post by I-try)
Pls help! I know that Intensity is directly proportional to Amplitude^2 but I don't understand why the answer here is D

Intensity directly porportional to square of amplitude:

I = k*A^2

If original intensity is I0 and final intensity is I1, then

I1/I0 = A1^2/A0^2

If I1 = 3*I0, then (3*I0)/I0= A1^2/A0^2

=> A1^2 = 3*A0^2

Square root both sides:

A1 = SQRT(3) * A0

Does that make sense?
3. Took me a while to get my head around that but wow! Thank you so much!!

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