IB+MYP+Light

Light from the previous year

Light Revision


 * __Grade 9 Physics Assessment Task: Light__ ||

**Investigation on 'Refraction of light from glass to air'**
You will be assessed on **Criterion D, E and F** for this task. Your task is to investigate the relationship between the angle of incidence and the angle of refraction of light from glass to air.


 * __1. Design__**

The critical angle is the angle at which light can be total reflected from a surface. The critical angle is determined by the refractive index of the medium that light is traveling in.

By investigating the relationship between the angle of incidence and the angle of refraction through a medium you can determine the refractive index of the medium. When the refractive index is known the critical angle for the medium can be calculated and experimentally confirmed

a. Design a method for the effective control of the variables.

b. Develop a method that allows for the collection of sufficient relevant data.


 * __2. Data Collection and Processing__**

a. Record the appropriate quantitative and associated qualitative raw data, including units.

b. Process the quantitative raw data correctly.

c. Presents processed data appropriately and, where relevant, includes errors.


 * __3. Conclusion and Evaluation__**

a. State a conclusion, with justification, based on a reasonable interpretation of the data.

b. Evaluate the weaknesses and limitations.

c. Suggest realistic improvements in respect of identified weaknesses and limitations.

You have been given this task sheet in advance so that you can think about the materials you need and plan an appropriate experiment that you can conduct in school. You will need to inform your teacher of equipment you need before you start the investigation. You can work in pairs but must write individual report to be submitted in 2 weeks from the date you were given this task sheet. Please attach the task sheet at the top of your report.

Due: 4th June 2012



=
The measure of the bending of a ray of light when passing from one medium into another. If //i// is the [|angle of incidence] of a ray in vacuum (angle between the incoming ray and the perpendicular to the surface of a medium, called the normal), and //r// is the [|angle of refraction] (angle between the ray in the medium and the normal), the refractive index //n// is defined as the ratio of the sine of the angle of incidence to the sine of the angle of refraction; //i.e., n// = sin //i// / sin //r//. Refractive index is also equal to the velocity //c// of light of a given wavelength in empty space divided by its velocity //v// in a substance, or //n// = //c/////v//.=====

1. Find out if the refractive index depends on the speed of light in the mateiral, or if it depends on the density of the material. You can do this by using the Chart Wizard to plot graphs to see if the data forms a pattern. 2. Explain how plotting graphs helped you to answer question 1.

Factors affecting refraction

(kg/m3) || Speed of light (million km/s) ||
 * Material || Refractive index || Density
 * vacuum || 1.0000 || 0 || 300.0 ||
 * air || 1.0003 || 1.2 || 299.9 ||
 * ice || 1.3100 || 917 || 229.0 ||
 * water || 1.3333 || 998 || 225.0 ||
 * alcohol || 1.3600 || 789 || 220.6 ||
 * plexiglass || 1.5100 || 1190 || 198.7 ||
 * crown glass || 1.5200 || 2500 || 197.4 ||
 * zircon || 1.9230 || 4500 || 156.0 ||
 * diamond || 2.4170 || 3500 || 124.1 ||