In a double slit experiment, instead of taking slits of equal widths, one slit is made twice as wide as the other. Then in the interference pattern

In interference between waves of equal amplitudes a, the minimum intensity is zero and the maximum intensity is proportional to 4a2. For waves of unequal amplitudes a and A(A >a), the minimum intensity is non zero and the maximum intensity is proportional to (a + A)2, which is greater than 4a2.