Definitions [3]
Definition: Diffraction of Light
The bending of light near the edge of an obstacle or slit and spreading into the region of geometrical shadow is called diffraction of light.
Definition: Fresnel Diffraction
The type of diffraction that occurs when the source or screen is at a finite distance from the diffracting object and fringes are not sharp and well-defined is called Fresnel diffraction.
Definition: Fraunhofer Diffraction
The type of diffraction that occurs when the source and the observation screen are far away (effectively at infinite distance) from the diffracting object and fringes are not sharp and well-defined is called Fraunhofer diffraction.
Important Questions [26]
- Derive the conditions of maxima and minima due to interference of light transmitted from thin film of uniform thickness.
- Obtain the condition for maxima and minima of the light reflected from a thin transparent film of uniform thickness. Why is the visibility of the fringe much higher in the reflected system
- What is Antireflection Coating? What Should Be the Refractive Index and Minimum Thickness of the Coating?
- Derive the conditions of maxima and minima due to interference of light reflected from thin film of uniform thickness.
- What is meant by thin film? Comment on the colours in thin film in sunlight.
- A wedge shaped air film having angle 40 seconds is illuminated by monochromatic light. Fringes are observed vertically through a microscope.
- Explain how interference in wedge shaped film is used to test optical flatness of given glass plate.
- What will be the fringe pattern if wedge shaped air film is illuminated with white light?
- A wedged shaped air film having an angle of 40 seconds is illuminated by monochromatic light and fringes are observed vertically through a microscope.
- A Parallel Beam of Light of Wavelength 5890 A0 is Incident on a Glass Plate Having Refractive Index 𝝁=𝟏.𝟓 Such that the Angle of Refraction in the Plate is 600. Calculate the Smallest Thickness
- A Newtons Rings Setup is Used with a Source Emitting Two Wavelength λ1=6000a0 and λ2=4500 A0. It is Found that Nth Dark Ring Due to 6000a0 Coincides with (N+2)Th Dark Ring Due to 4500 A0.
- Why the Newton’s rings are circular and fringes in wedge shaped film are straight?
- With Newton’s ring experiment explain how to determine the refractive index of liquid.
- In Newtons’s ring experiment,what will be the order of dark ring which will have double the diameter of 40th dark ring?
- Explain Newton’S Ring Experiment and Show that Diameters of Nth Dark Rings Are Proportional to Square Root of Natural Numbers.
- With the Help of Proper Diagram and Necessary Equation, Explain How Newtons Ring Experiment is Useful to Determine the Radius of Curvature of Plano Convex Lens.
- Why the Newton’S Rings Are Circular and Centre of Interference Pattern (Reflected) is Dark?
- Describe in detail the concept of anti-reflecting film with a proper ray diagram.
- What is Diffraction Grating and Grating Element? Explain Experimental Method to Determine the Wavelength of the Spectral Line Using Diffraction Grating?
- Discuss the Fraunhoffer diffraction at single slit and obtain the condition for minima.
- Derive the Condition for Absent Spectra in Grating.
- What is grating and grating element?
- Explain the Experimental Method to Determine the Wavelength of Spectral Line Using Diffraction Grating.
- What is diffraction grating? What is the advantage of increasing the number of lines in the grating?
- What is Rayleigh’s criterion of resolution? Define resolving power of grating?
- Explain the experimental method to determine the wavelength of spectral lines using grating. A diffraction grating has 5000 lines / cm and the total ruled with is 5cm.
Concepts [19]
- Interference by Division of Amplitude and by Division of Wave Front
- Interference in Thin Film of Constant Thickness Due to Reflected and Transmitted Light
- Origin of Colours in Thin Film
- Wedge Shaped Film(Angle of Wedge and Thickness Measurement)
- Newton’S Rings
- Applications of Interference - Determination of Thickness of Very Thin Wire Or Foil
- Determination of Refractive Index of Liquid
- Wavelength of Incident Light
- Radius of Curvature of Lens
- Testing of Surface Flatness
- Anti-reflecting Films and Highly Reflecting Film
- Diffraction of Light
- Fraunhoffer Diffraction at Single Slit
- Fraunhoffer Diffraction at Double Slit
- Diffraction Grating
- Resolving Power of a Grating
- Dispersive Power of a Grating
- Application of Diffraction
- Determination of Wavelength of Light with a Plane Transmission Grating
