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Optics bench
Ray Table and Base
Slit Plate
Cylindrical Lens
Light source
component Holder
Slit Mask

As you haver seen, the direction of light propagation changes abruptly when light encounters a reflective surface. The direction also changes abruptly when light passesacross a boundary between two different media of propagation, such as between air and acrylic, or between glassand water. In this case, the change of direction is called Refrantion.

As for reflection, a simple law characterizes the behavior of a refracted ray of light. According to the Law of Refraction, also known as Snell's Law:

The quantities n1 and n2 are constants,called indices of refraction, that depend on the two media through which the light is passing. The angles teta1 and teta2 are theangles that the ray of light makes with the normal to the boundary between the two media (see the insert in Figure 4.1). In this experiment you will test the validity of this law, and also measure the index of refraction for acrylic.

PROCEDURE

Set up the equipment as shown in Figure 4.1. Adjust the components so a single ray of light passes directly through the center of the Ray Table DegreeScale, Align the flat surface of the Cylindrical Lens whit the line labeled "component". Whit the lens properly aligned, the radial lines extending from the center of the DegreeScale will all be perpendicula to the circular surface of the lens.


Whitouth disturbing the alignment of the Lens, rotate the Ray Table and observe the refracted ray for various angles of incidence.

1. Is the ray bentwhen it passes into the lens perpendicular to the flat surface of the lens ?

2. Is the ray bent when it passes out of the lens perpendicular to the surface of the lens ?

By rotating the Ray Table, set the angle of incidende to each of the settings shown in Table 4.1 on the following page. For each angle of incidence, measure the angle of refraction (refraction 1). Repeat the measurementwhit the incident ray striking from the opposite side of the normal (refraction 2)

3. Are your results for the two sets of measurements the same ? If not, to what do you attribute the differences ?

On a separate sheet of paper, construct a graph whit sin(angle of refraction) on the x-axis and sin(angle of incidence) on the y-axis. Draw the best fit straight line for each of your two sets ofdata.

4. Is your graph consistent whit the Law of Refraction ? Explain

5. Measure the slope of your best fit lines, Take the average of your results to determine the index of refraction for acrylic (asume that the index of refraction for air is equal to 1.0)

ADDITIONAL QUESTIONS

1. In performing the experiment, what difficulties did you encounter in measring the angle of refraction forlarge angle of incidence ?
2. Was all the light of the ray refracted ? Was some reflected ? How might you have used the Law of refletcion to test the alignment of Cylindrical Lens ?
3. How does averaging the results of measurements taken with the incident ray striking from either side of the normal improve the accuracy of the results ?

TRADUCTION

Óptica banco
Ray Tabla y Base
Placa dehendidura
lente cilíndrica
fuente de luz
Holder componente
Máscara de hendidura

Como has visto haver , la dirección de propagación de la luz cambia abruptamente cuando la luz se encuentra con una superficie reflectante. La dirección también cambia abruptamente cuando la luz passesacross un límite entre dos medios diferentes de propagación , por ejemplo, entre el aire y el acrílico , o entre elvidrio y el agua. En este caso , el cambio de dirección se llama Refrantion .

En cuanto a la reflexión, una simple ley que caracteriza el comportamiento de un rayo refractado de luz. De acuerdo con la ley de la refracción , también conocida como la ley de Snell :

Las cantidades n1 y n2 son constantes , llamados índices de refracción , que dependen de los dos medios de comunicación a través...