• facebook
  • twitter
  • whatsapp
  • telegram

Wave Optics

Questions - Answers

Short Answer Questions:

1. Explain how plane polarized light is obtained by reflection?
A: (1) All the light vectors vibrating in different directions of an unpolarized light can be grouped into two mutually perpendicular components.
i) Vibrations parallel to the plane of the paper called arrow (↔) components.
(ii) Vibrations perpendicular to the plane of the paper called dot (.) components.
The ordinary light (unpolarized light) is represented by showing arrows and dots simaltaneously.
(2) In fig. an unpolarized light AB falls on transparent medium like glass. The reflected ray consists of dot components only.    

The vibrations of light vectors are perpendicular to plane of incidence. The amount of polarized light depends on angle of incidence i.
(3) For a particular angle i the reflected light is completely polarized. This angle is known as Brewster's angle. At Brewsters angle reflected ray and refracted ray are mutually perpendicular. The relation between refractive index µ and Brewster angle is µ = tan i.
When light falls on a transparent medium with Brewsters angle then we will get polarized light by reflection.

 

2. Explain double refraction (Birefringence) of light.
A: Double refraction: When light passes through quartz or calcite. Crystal the refracted ray is divided into two parts called ordinary ray and extraordinary ray. Both the rays are plane polarized. Their plane of vibrations are perpendicular to each other.


          
r1 = Angle of refraction for ordinary ray    r2 = Angle of refraction for extraordinary ray

1) Ordinary ray: The light ray which follows Snell's law is called ordinary ray. For this ray refractive index µ and velocity of light is same through out that medium. Secondary wavefront of ordinary ray is spherical.
2) Extraordinary ray: The light ray which does not obey Snell's law is called extraordinary ray. For this ray refractive index and velocity changes with direction. It does not follow Snell's law. Extraordinary ray will have different refractive indices depending on direction of travel or angle of incidence. The secondary wavefront of extraordinary ray is ellipsodial. Along the optical axis of the crystal the e-ray and o-ray have same speed.
When a calcite or quartz crystal is rotated then the image formed by extraordinary ray will rotate around the image formed by ordinary ray.

 

3. Mention some applications of diffraction.
A: 1) The wavelength of light is measured accurately by using diffraction gratings. This technique can be used for monochromatic light or for composite light.
2) Wavelength of X - rays can be accurately measured by using X - ray diffraction techniques.
3) Structure of crystalline solids can be determined by using X - ray. Electron and Neutron diffraction.

4) Velocity of sound in liquids can be estimated with the help of ultrasonic diffraction techniques.
5) Ultra sound scanning is based on diffraction of ultrasonic sound waves.

 

4. What are the applications of polarization of light?
A: 1) Polarized light is used to test and measure optical activity of the crystals like quartz.
2) Optical activity of organ substances like glucose solutions etc., is measured with polarized light.
3) Polarized light can be used to study the helical structure of nuclear acids.
4) Polarizing glasses reduces the intensity of light falling on the eyes and reduces the damaged or retina.

Posted Date : 14-10-2020

గమనిక : ప్రతిభ.ఈనాడు.నెట్‌లో కనిపించే వ్యాపార ప్రకటనలు వివిధ దేశాల్లోని వ్యాపారులు, సంస్థల నుంచి వస్తాయి. మరి కొన్ని ప్రకటనలు పాఠకుల అభిరుచి మేరకు కృత్రిమ మేధస్సు సాంకేతికత సాయంతో ప్రదర్శితమవుతుంటాయి. ఆ ప్రకటనల్లోని ఉత్పత్తులను లేదా సేవలను పాఠకులు స్వయంగా విచారించుకొని, జాగ్రత్తగా పరిశీలించి కొనుక్కోవాలి లేదా వినియోగించుకోవాలి. వాటి నాణ్యత లేదా లోపాలతో ఈనాడు యాజమాన్యానికి ఎలాంటి సంబంధం లేదు. ఈ విషయంలో ఉత్తర ప్రత్యుత్తరాలకు, ఈ-మెయిల్స్ కి, ఇంకా ఇతర రూపాల్లో సమాచార మార్పిడికి తావు లేదు. ఫిర్యాదులు స్వీకరించడం కుదరదు. పాఠకులు గమనించి, సహకరించాలని మనవి.

Special Stories

More

విద్యా ఉద్యోగ సమాచారం

More
 

లేటెస్ట్ నోటిఫికేష‌న్స్‌