Two waves having amplitudes in the ratio $5:1$ produce interference. The ratio of the maximum to minimum intensity is

Two waves of intensity $I$ undergo interference. The maximum intensity obtained is

$A$ and $B$ are two interfering sources where $A$ is ahead in phase by $54^{\circ}$ relative to $B$. The observation is taken from point $P$ such that $PB-PA=2.5 \lambda$. Then the phase difference between the waves from $A$ and $B$ reaching point $P$ is (in rad) (in $\pi$)

If an interference pattern has maximum and minimum intensities in a $36:1$ ratio,then what will be the ratio of the amplitudes?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: The phase difference of two light waves changes if they travel through different media having the same thickness,but different indices of refraction.
Reason $R$: The wavelengths of waves are different in different media.
In the light of the above statements,choose the most appropriate answer from the options given below.

For obtaining maximum contrast between the bright and dark fringes in an interference pattern, the intensities of the two light coherent sources should be