Wave interference intensity ratio

Steps:

• Maximum resultant amplitude = sum of individual amplitudes = a + b.
• Minimum resultant amplitude = difference of individual amplitudes = |a - b|.
• Intensity I ∝ (amplitude)^2, so I_max ∝ (a + b)^2 and I_min ∝ (a - b)^2.
• Ratio I_max / I_min = [(a + b)/(a - b)]^2; for a:b = 5:3, this equals (8/2)^2 = 16.

Why D is correct:

• Superposition principle gives intensity ratio as square of (sum/difference) of amplitudes; for 5:3 ratio, it is exactly 16.

Why the others are wrong:

• A. 1.7 approximates amplitude ratio 5:3 ≈1.67, not intensity ratio.
• B. 2.8 approximates (5:3)^2 ≈2.78, ratio of individual intensities.
• C. 4.0 is intensity ratio for amplitude ratio 3:1, [(4/2)^2=4].

Final answer: D