Question

When two coherent waves interfere, the maximum and minimum intensities are in the ratio 25:16. Then,
a) the maximum and minimum amplitudes are in the ratio 5 : 4
b) the amplitudes of individual waves are in the ratio 9 : 1
c)the intensities of individual waves are in the ratio 41: 9
d) the intensities of individual waves are in the ratio 81 : 1

• A. a, b and c are true
• B. a,b and d are true
• C. a and b are true
• D. b and c are true

Answer 1

The correct option is B a,b and d are true

If maximum and minimum intensities are in ratio $\frac{25}{16}$
Then amplitudes are in ratio $\frac{5}{4}$ as amplitude is proportional to the square root of Intensity.
Let individual waves be $a_1$ and $a_2$
Then $\frac{a_1+a_2}{a_1-a_2}=\frac{5}{4}$
We get $a_1:a_2=9:1$
Intensities are proportional to the square of amplitude.
Ratio of Intensities $I_1:I_2=81:1$