Problems on intensity of coherent source

In Young's Double Slit Experiment, there is the formation of different intensities of light on the screen.

In the experiment, light is allowed to pass through two slits.

After light passes through the two slits, it form some patterns on the screen kept at some distance.

These patterns are the formation of different intensities of light.

The different intensities of light is due to a phenomenon known as interference.

Now let's discuss the practical problem on the interference of light.

The intensity of two coherent sources is in the ratio 9:4.

And we are interested in calculating the ratio of maximum intensity and minimum intensity in the interference patter.

So, let's proceed with the solution of the problem.

First, we will convert the intensity of light in terms of the amplitude,

The ratio of both the amplitude is given as,

Then, the ratio of maximum and minimum intensity in terms of amplitude,

The value of the ratio of maximum and minimum intensity is,

Now, we will consider another situation on the interference of light

If the width of two slits is in the ratio $4:1$. And we are interested in finding the ratio of the amplitude two interfering waves?

And we know the relation between the slit width, intensity and amplitude which is given as,

Next, the relation between the intensity and amplitude is given as,

The value of the ratio of amplitude is given as,

So, we have understood the different methods to solve the numerical problem.

The End