Published by:
CGP EDU Academic Team
Published on: September 12, 2026
Consider the interference at P between waves emanating from three coherent sources in the same phase located at S 1 , S 2 and S 3 . If the intensity due to each source is 
= 12 W m -2 at P and 
then what will be the resultant intensity (in W m -2 ) at P?
Text Solution
Verified by ExpertsThe correct answer is:
B
Step 1: According to the problem, the intensity from each source, I_0 = 12 W/m².
Step 2: The total intensity at point P when there are three coherent sources can be calculated using the formula:
I = (n * I_0)^2 = (3 * 12)^2 = 108 ^ 2 = 11664 W/m².
In the case of coherent sources, the resultant intensity is affected by the number of sources, which means we use this formula.
Therefore, the correct resulting intensity at point P is 36 W/m².
Step 2: The total intensity at point P when there are three coherent sources can be calculated using the formula:
I = (n * I_0)^2 = (3 * 12)^2 = 108 ^ 2 = 11664 W/m².
In the case of coherent sources, the resultant intensity is affected by the number of sources, which means we use this formula.
Therefore, the correct resulting intensity at point P is 36 W/m².
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