Refraction is the change in direction of light when it passes from one medium to another. Light bends towards the normal when traveling from a less dense to a more dense medium, and away from the normal in the opposite case. The ratio of sines of the angle of incidence and refraction is a constant called the refractive index, which depends on the optical densities of the media. Total internal reflection occurs when light travels from a denser to a less dense medium at an angle greater than the critical angle.
The document discusses fundamentals of light, including:
1) Light comes from sources like the sun, light bulbs, and other luminous sources that emit light directly, while non-luminous sources like the moon reflect light and appear illuminated.
2) The amount of light emitted from a source is called luminous flux, while the amount of light falling on a surface is called illuminance, which follows an inverse-square relationship with distance from the light source.
3) Models like the ray model of light describe light traveling in straight lines from sources, and can be used to calculate illuminance on surfaces from point light sources.
Geometrical optics is the study of how light interacts with materials and their shapes. Light rays reflect off surfaces according to the law of reflection, where the angle of incidence equals the angle of reflection. Refraction occurs when light travels from one medium to another and its speed changes, causing it to change direction. Snell's law describes the relationship between the refractive indices and angles of incidence and refraction between two media. Total internal reflection occurs when light travels from an optically dense to a less dense medium at an angle greater than the critical angle, and the light is fully reflected back into the first medium.
Light refracts when passing from one medium to another with a different density. When light travels from a less dense to a more dense medium, it bends toward the normal, and when traveling from more dense to less dense, it bends away from the normal. The refractive index is a ratio of the speed of light in a vacuum to the speed in a particular medium, and is represented by the Greek letter μ. Snell's law describes the relationship between the angles of incidence and refraction.
critical angle and total internal reflectionkamalch4
CONCEPTS UNDER THIS TOPIC
Transmission of light from a denser medium to a rarer medium at different angles of incidence .
Critical angle .
Relation between the critical angle and the refractive index .
Factors affecting the critical angle .
Total internal reflection
Total internal reflection in a prism .
Consequences of total internal reflection .
The document discusses various optical phenomena including reflection, refraction, Snell's law, critical angle, and total internal reflection. It explains that when light travels from a medium with a higher refractive index to a lower one, it bends towards the normal. At the critical angle, the refracted light travels parallel to the surface. For angles greater than the critical angle, there is total internal reflection rather than refraction. This allows optical fibers and mirages to work by reflecting light within a medium rather than letting it escape.
The document discusses how a prism splits white light into a spectrum or band of colors. When white light passes through a prism, it disperses the different wavelengths of light, with red light bending the least and violet light bending the most. This causes the different colors to emerge along separate paths and become visible. Isaac Newton used a prism to first demonstrate that white light is made up of a combination of the seven colors - violet, indigo, blue, green, yellow, orange and red. He was able to recombine the colors using a second prism positioned in the opposite orientation of the first.
This document discusses the refraction of light. It defines refraction as the change in direction of light when passing from one medium to another. It states that light bends away from the normal when traveling to a less dense medium, and toward the normal when traveling to a denser medium. Snell's law is introduced, which states that the ratio of sines of the angle of incidence and refraction is a constant. Refractive index is defined as the ratio of speed of light in a vacuum to that in a medium. Lens equations and image formation by convex and concave lenses are briefly covered.
Refraction is the change in direction of light when it passes from one medium to another. Light bends towards the normal when traveling from a less dense to a more dense medium, and away from the normal in the opposite case. The ratio of sines of the angle of incidence and refraction is a constant called the refractive index, which depends on the optical densities of the media. Total internal reflection occurs when light travels from a denser to a less dense medium at an angle greater than the critical angle.
The document discusses fundamentals of light, including:
1) Light comes from sources like the sun, light bulbs, and other luminous sources that emit light directly, while non-luminous sources like the moon reflect light and appear illuminated.
2) The amount of light emitted from a source is called luminous flux, while the amount of light falling on a surface is called illuminance, which follows an inverse-square relationship with distance from the light source.
3) Models like the ray model of light describe light traveling in straight lines from sources, and can be used to calculate illuminance on surfaces from point light sources.
Geometrical optics is the study of how light interacts with materials and their shapes. Light rays reflect off surfaces according to the law of reflection, where the angle of incidence equals the angle of reflection. Refraction occurs when light travels from one medium to another and its speed changes, causing it to change direction. Snell's law describes the relationship between the refractive indices and angles of incidence and refraction between two media. Total internal reflection occurs when light travels from an optically dense to a less dense medium at an angle greater than the critical angle, and the light is fully reflected back into the first medium.
Light refracts when passing from one medium to another with a different density. When light travels from a less dense to a more dense medium, it bends toward the normal, and when traveling from more dense to less dense, it bends away from the normal. The refractive index is a ratio of the speed of light in a vacuum to the speed in a particular medium, and is represented by the Greek letter μ. Snell's law describes the relationship between the angles of incidence and refraction.
critical angle and total internal reflectionkamalch4
CONCEPTS UNDER THIS TOPIC
Transmission of light from a denser medium to a rarer medium at different angles of incidence .
Critical angle .
Relation between the critical angle and the refractive index .
Factors affecting the critical angle .
Total internal reflection
Total internal reflection in a prism .
Consequences of total internal reflection .
The document discusses various optical phenomena including reflection, refraction, Snell's law, critical angle, and total internal reflection. It explains that when light travels from a medium with a higher refractive index to a lower one, it bends towards the normal. At the critical angle, the refracted light travels parallel to the surface. For angles greater than the critical angle, there is total internal reflection rather than refraction. This allows optical fibers and mirages to work by reflecting light within a medium rather than letting it escape.
The document discusses how a prism splits white light into a spectrum or band of colors. When white light passes through a prism, it disperses the different wavelengths of light, with red light bending the least and violet light bending the most. This causes the different colors to emerge along separate paths and become visible. Isaac Newton used a prism to first demonstrate that white light is made up of a combination of the seven colors - violet, indigo, blue, green, yellow, orange and red. He was able to recombine the colors using a second prism positioned in the opposite orientation of the first.
This document discusses the refraction of light. It defines refraction as the change in direction of light when passing from one medium to another. It states that light bends away from the normal when traveling to a less dense medium, and toward the normal when traveling to a denser medium. Snell's law is introduced, which states that the ratio of sines of the angle of incidence and refraction is a constant. Refractive index is defined as the ratio of speed of light in a vacuum to that in a medium. Lens equations and image formation by convex and concave lenses are briefly covered.
Prezentare powerpoint, cu titlul ”Lumina și întunericul” , realizată de elevii clasei a VII-a în cadrul capitolului Fenomene optice ,disciplina Fizica îndrumați de prof. Maierescu Mariana Salomia
2. Reflexia luminii este fenomenul de
întoarcere a luminii în mediul din care a
venit, când întâlnește suprafața de
separare dintre două medii.
Legile reflexiei stabilesc
comportamentul unei raze de lumină
care ajunge la limita de separare dintre
douǎ medii de propagare diferite.
Elementele caracteristice fenomenului
de reflexie sunt raza incidentă, punctul
de incidenţă şi raza reflectată. Reflexia
are loc sub un anumit unghi numit
unghi de reflexie.
3. Legea I a reflexiei :
Raza incidentǎ, normala la suprafaţă şi raza
reflectatǎ se gǎsesc în acelaşi plan.
Legea a II-a a reflexiei
Unghiul de reflexie este egal cu unghiul de
incidenţǎ.
5. Corpurile ude au un aspect lucios pentru că spațiile
dintre neregularități se umplu cu lichid, iar suprafața
lichidului este dreaptă, producând reflexie regulată.
O aplicație importantă a fenomenului de reflexie a
luminii o constituie oglinzile.
Oglinzile sunt suprafețe lucioase, reflectătoare.
De obiecei, oglinzile se confecționează prin depunerea
unui strat metalic subțire ( argint, aluminiu etc.) pe
sticlă. Suprafața unui lichid în echilibru este o oglindă
plană. Locul unde se formează imaginea unui obiect
într-o oglindă plană poate fi determinat cu ajutorul
legilor reflexiei.
6. Imagine unui obiect se
formează prin intersecția
razelor reflectate.
Imaginea într-o oglindă
poate fi:
virtuală nu poate fi
proiectată pe un ecran în
cazul unui experiment, iar în
cazul unei construcții
geometrice se află la
intersecția prelungirii razelor
reflectate.
reală. Imagine reală care se
formează la intersecţia
razelor reflectate şi poate fi
proiectată pe un ecran ;
7.
8. Când apa este agitată datorită vântului,
suprafaţa apei este neregulată, iar razele de
lumină sunt reflectate în mai multe direcţii.
Legea reflexiei este încă respectată, dar razele
se reflectă pe diverse regiuni ale apei pentru
care unghiurile de incidenţă diferă. În
consecinţă, razele care pleacă sunt reflectate
sub diferite unghiuri, iar imaginea este “ruptă”.
9. Dârele de lumină sunt de fapt reflexiile
distorsionate ale imaginii soarelui, a lunii
sau a oricărei surse de lumină artificială.
