17.1 How Light Behaves at a Boundary By Victoria Skinner Light travels in a straight line and at very high velocities. *Its velocity varies depending on the medium it moves through. 17.1 How Light Behaves at a Boundary

law of reflection *If 2 parallel beams strike a mirror 2 reflected beams are also parallel *If a line is perpendicular to a mirror it is the normal because it is normal to the surface.

*regular reflection- happens when light is reflected back to the observer in parallel beams *Diffuse reflection- the scattered, fuzzy reflection from a rough surface where light is reflected reflections *There are not always  reflected beams sometimes there are just fuzzy dots such as when a surface is smooth and not transparent.

Refraction of light

Angle of refraction Angle of refraction- the angle the refracted ray makes with the normal to the surface

Optically dense Optically dense- materials with larger indices of refraction with respect to other materials

Snell’s law *Snell's law- states that the ratio of sine of the angle  of refraction is a constant Incident Ray traveling in a less dense medium

index of refraction *index of refraction- the ratio of the speed of light in a vacuum to its speed in a material* *The index of refraction often can be measured by directing a ray of light onto the substance's surface, measuring the angle of incidents and angle of refraction,then using Snell’s law..

problem solving strategies- 1.draw a diagram showing 2 media and label 2. Draw the incident ray 3.use protractor 4.use Snell’s law 5.use protractor 6.evaluate. *when solving problems involving refractions and reflections of light a one will use a ray diagram . * when setting up a Snell's law problem assign symbols for the various quantities, and check your results. When light passes through a medium it is reflected or refracted. *The degree to witch the light is bent depends on the angle of incidence and the properties of the medium. *On can find how the angle of refraction depends on the angle of incidence by using the Snell's law

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