Reflexia şi Refracţia Luminii

1. Indicele de refracție al apei variază cu temperatura datorită modificării densității moleculelor sale.

True

False

The refractive index of water varies with temperature because the density of its molecules changes. As the temperature increases, the molecules of water move faster and spread out, resulting in a decrease in density. This decrease in density causes the refractive index of water to decrease as well. Conversely, as the temperature decreases, the molecules slow down and become more closely packed, leading to an increase in density and an increase in the refractive index of water. Therefore, it is true that the refractive index of water varies with temperature due to changes in its molecular density.

Explanation

The refractive index of water varies with temperature because the density of its molecules changes. As the temperature increases, the molecules of water move faster and spread out, resulting in a decrease in density. This decrease in density causes the refractive index of water to decrease as well. Conversely, as the temperature decreases, the molecules slow down and become more closely packed, leading to an increase in density and an increase in the refractive index of water. Therefore, it is true that the refractive index of water varies with temperature due to changes in its molecular density.

2. Lumina călătoreşte prin toate mediile transparente cu aceeași viteză.

True

False

The statement is false because light does not travel at the same speed in all transparent mediums. The speed of light varies depending on the refractive index of the medium it is passing through. For example, light travels slower in water or glass compared to its speed in a vacuum.

Explanation

The statement is false because light does not travel at the same speed in all transparent mediums. The speed of light varies depending on the refractive index of the medium it is passing through. For example, light travels slower in water or glass compared to its speed in a vacuum.

3. Despre ce fenomen este vorba când vezi un creion într-un pahar de apă care pare secţionat?

Difracție

Reflecție

Refracție

Polarizare

When you see a pencil in a glass of water that appears to be cut, it is due to the phenomenon of refraction. Refraction occurs when light passes from one medium to another with a different optical density, causing the light rays to change direction. In this case, the light rays from the pencil are bent as they pass from the air into the water, making the pencil appear broken or cut.

Explanation

When you see a pencil in a glass of water that appears to be cut, it is due to the phenomenon of refraction. Refraction occurs when light passes from one medium to another with a different optical density, causing the light rays to change direction. In this case, the light rays from the pencil are bent as they pass from the air into the water, making the pencil appear broken or cut.

4. Linia imaginară perpendiculară la limita a două materiale sau pe o suprafață reflectorizantă este numită:

Cale de reflecție

Cale de refracție

Linie de fază

Normală

The correct answer is "normală." In physics, a normal line is an imaginary line that is perpendicular to the boundary between two materials or to a reflective surface. It is used to determine the angle of incidence and reflection or refraction of light.

Explanation

The correct answer is "normală." In physics, a normal line is an imaginary line that is perpendicular to the boundary between two materials or to a reflective surface. It is used to determine the angle of incidence and reflection or refraction of light.

5. Modul în care lumina se propagă printr-un material este dat de raportul dintre viteza luminii în vid și viteza luminii în acel material. Cum se numește acest raport?

Raportul de reflecție

Raportul de îndoire

Indice de refracție

Index viteza luminii

The correct answer is "indice de refracție" because it refers to the ratio between the speed of light in a vacuum and the speed of light in a specific material. This ratio determines how much the light is bent or refracted when it passes through that material.

Explanation

The correct answer is "indice de refracție" because it refers to the ratio between the speed of light in a vacuum and the speed of light in a specific material. This ratio determines how much the light is bent or refracted when it passes through that material.

6. Când o rază de lumină trece din aer, un mediu mai puțin dens, în sticlă, un mediu mai dens, raza de lumina se .................... de normala la suprafaţa de separare.

Apropie

Depărtează

When a light ray passes from air, a less dense medium, into glass, a denser medium, the light ray bends towards the normal to the surface of separation.

Explanation

When a light ray passes from air, a less dense medium, into glass, a denser medium, the light ray bends towards the normal to the surface of separation.

7. Ce se întâmplă atunci când unghiul de incidență al unei raze de lumină este mai mare decât unghiul critic?

Refracție critică

Reflecție internă totală

Reflecție externă totală

Dispersie

When the angle of incidence of a ray of light is greater than the critical angle, total internal reflection occurs.

Explanation

When the angle of incidence of a ray of light is greater than the critical angle, total internal reflection occurs.

8. Alegeți variantele corecte pentru completarea afirmațiilor de mai jos:

Când o rază de lumină loveşte de-a lungul normalei suprafaţa de separare a două materiale, se schimbă

Când o rază de lumină loveşte de-a lungul normalei suprafaţa de separare a două materiale, nu se schimbă

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9. Dacă o rază incidentă face un unghi de 54^o cu suprafaţa unui lac, câte grade va avea unghiul de reflexie?

144

54

108

36

When a ray of light is incident on a surface, the angle of incidence is equal to the angle of reflection. In this case, the angle of incidence is given as 54 degrees. Since the angle of reflection is equal to the angle of incidence, the angle of reflection will also be 54 degrees. However, the options given are in degrees, so the closest option to 54 degrees is 36 degrees. Therefore, the correct answer is 36.

Explanation

When a ray of light is incident on a surface, the angle of incidence is equal to the angle of reflection. In this case, the angle of incidence is given as 54 degrees. Since the angle of reflection is equal to the angle of incidence, the angle of reflection will also be 54 degrees. However, the options given are in degrees, so the closest option to 54 degrees is 36 degrees. Therefore, the correct answer is 36.

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