Michelson Interferometer - Part 1 | Construction and find Wavelength | explained in HINDI

Summary

The video script discusses the concept of interference, specifically focusing on the use of monochromatic light and its applications. It explains how to determine the wavelength of light using a monochromatic source and a device called an interferometer. The script also covers basic applications like measuring the thickness and refractive index of a transparent material. The video explains the construction and working of the interferometer, the generation of light waves, and their behavior when interacting with mirrors and a glass slab. It further delves into the interference pattern formation on a screen, the effect of rotating a knob to alter the pattern, and the principles behind constructive and destructive interference. The script concludes by hinting at future discussions on calculating the wavelength of monochromatic light sources.

Takeaways

• 🔬 The discussion focuses on the interference phenomenon and its basic applications, particularly determining the wavelength of monochromatic light.
• 🔭 Applications include measuring the thickness and refractive index of a thin transparent material, as well as the refractive index of a gas.
• 📡 The construction of the interferometer is described, which includes a monochromatic light source, a lens, a glass slab, and two mirrors (m1 and m2).
• 🌟 Light from the source passes through the lens, reflects off the mirrors, and interferes upon returning to the screen, creating a pattern of fringes.
• 🔄 Rotating a knob adjusts the position of the mirrors, which affects the interference pattern visible on the screen, causing the fringes to expand or contract.
• 🔍 The concept of constructive and destructive interference is explained, depending on the path difference between the light waves.
• 📏 The path difference is crucial in determining the interference pattern, and it is directly related to the distance the mirrors move.
• 🔄 As the mirrors move, the phase difference between the light waves changes, shifting the interference pattern from constructive to destructive and vice versa.
• 📉 The pattern of fringes on the screen changes as the mirrors are adjusted, with fringes appearing to move towards or away from the center.
• ⏱️ The video concludes with a discussion on how the number of 'cross-overs' in the interference pattern can be used to calculate the wavelength of the monochromatic light source.

Q & A

What is the basic application of interference discussed in the script?

The basic application of interference discussed is determining the wavelength of monochromatic light by using a monochromatic light source.

How can we find the thickness and refractive index of a thin transparent material using interference?

By analyzing the interference pattern produced when light passes through a thin transparent material, one can determine its thickness and refractive index.

What is the role of mirrors in the interference experiment described in the script?

Mirrors in the experiment are used to reflect light waves, which then interfere with each other to create an interference pattern on a screen.

Why does the interference pattern change when the knob is rotated in the experiment?

Rotating the knob changes the path difference between the two light waves, which in turn alters the interference pattern observed on the screen.

What is the significance of the term 'web length' in the context of the script?

The 'web length' refers to the path difference introduced by the optical setup, which is crucial for the interference pattern formation.

How does the movement of the mirror affect the interference pattern in terms of path difference?

Moving the mirror changes the path difference between the two light waves, which can lead to constructive or destructive interference, depending on whether the path difference is an integer multiple of the wavelength or not.

What happens when the phase difference between the two light waves is 180 degrees?

When the phase difference between the two light waves is 180 degrees, destructive interference occurs, leading to a dark fringe in the interference pattern.

What is the relationship between the fringes observed on the screen and the path difference?

The fringes observed on the screen correspond to different path differences between the interfering light waves, with constructive interference occurring at integer multiples of the wavelength and destructive interference at odd multiples of half the wavelength.

How can the wavelength of monochromatic light be determined from the interference pattern?

By counting the number of times the interference pattern repeats (cross-overs) and knowing the path difference introduced by the optical setup, one can calculate the wavelength of the monochromatic light using the formula that relates path difference to the wavelength.

What is the purpose of rotating the knob in the experiment?

Rotating the knob in the experiment is used to adjust the path difference between the two light waves, which allows for the observation of how the interference pattern changes and ultimately helps in determining the wavelength of light.

What is the term used to describe the point where the central maximum of the interference pattern disappears?

The term used to describe the point where the central maximum disappears is 'crossing over,' which signifies a change in the interference pattern due to the adjustment of the optical setup.