Seeing Things Through Stuff 1)Stare straight ahead at the word “Refraction” on the blackboard. 2)Close your right eye. 3)Hold the index finger of your right hand in a horizontal position, pointing forward, at arm’s length away from your side.

4)Wiggling your finger helps. 5)While still staring straight ahead, slowly rotate your right arm forward until you can just see your index finger with the peripheral vision of your left eye. 6)Rotate your left eye, not your head, to look at your index finger. 7) What happens?

8)Light that just passes by your nose strikes the eye’s lens and refracts (bends) into your eye.

9)When you rotate your left eye. your finger should disappear behind your nose. 10)There is no straight line path between your finger and retina (light sensitive part at the back of your eye). 11)How do eyeglasses effect this phenomenon?

No Glasses

With Glasses When wearing glasses, light can start to bend (refract) farther from the eye. The arm does not have to rotate as far before it can be seen.

What light travels through is called the Medium. The bending of light when it passes into a different medium is called Refraction. All transparent materials (e.g., glass, plastic, water, diamond, etc.) refract light. These materials are said to be Optically Dense. Note in this case, the light is traveling from an Optically Less Dense material (like air) to an Optically More Dense material (like glass and water).

The bending of light when it passes into a different medium is called Refraction. The “Incident Ray” (Incoming Ray) is the ray which meets the different medium at the “Point of Incidence”. Refraction Nomenclature

The “Refracted Ray” is the ray which has bent into the new medium. Refraction Nomenclature The bending of light when it passes into a different medium is called Refraction.

The “Angle of Incidence (  i)” is the angle between the incidence ray and the normal. Refraction Nomenclature The bending of light when it passes into a different medium is called Refraction.

The “Angle of Refraction (  R)” is the angle between the refracted ray and the normal. Refraction Nomenclature The bending of light when it passes into a different medium is called Refraction.

Your Turn Do L10 Refraction of Light Activity from Air (Less Dense) to Water (More Dense)) A Bird Can’t Fly On One Wing (Scottish or Irish proverb - Exact origins lost to time) In science, theory must always balance with observation.

1)Fill the semicircular container about three quarters full with water. L10 Refraction of Light Activity from Air (Less Dense) to Water (More Dense))

2)Carefully move the container so that it lines up with the image on the protractor.

2)Carefully move the prism so that it lines up with the image on the protractor.

3)Direct a single incident ray of light at the semicircular prism, along the 70º angle marked on the protractor.

4)Make absolutely sure that the ray passes through the centre of the flat surface. Measure the angle of refraction (  R) and record it in the table.

5)Repeat the procedure for angles of incidence of 60 , 50 , 40 , 30 , 20 , 10 , and 0 , recording your observations in the table.

When finished recording your observations, answer the analysis questions. Answers follow. L10 Refraction of Light Activity from Air (Less Dense) to Water (More Dense)

1)When light travels from air into glass along the normal, it does not bend; it travels straight through. OR  i =  R = 0º

2)When light travels from air to water at an angle of incidence greater than 0º,, it bends (away from / towards) the normal.

3)When light travels from air into glass, as the angle of incidence ( ∠ i) gets smaller, the angle of refraction ( ∠ R) … a) gets greater, b) becomes equal, c) gets smaller.

3)When light travels from air into glass, as the angle of incidence ( ∠ i) gets smaller, the angle of refraction ( ∠ R)… a) gets greater, b) becomes equal, c) gets smaller.

3)When light travels from air into glass, as the angle of incidence ( ∠ i) gets smaller, the angle of refraction ( ∠ R)… a) gets greater, b) becomes equal, c) gets smaller.

4)The incident and refracted rays are always on the (same side / opposite side), of the normal. 5)The angle of refraction ( ∠ R) is always a) greater than the angle of incidence ( ∠ i),,, b) less than the angle of incidence ( ∠ i), c) equal to the angle of incidence ( ∠ i).

6)Draw the refracted ray. The grey dotted line is the undeviated path for the light to travel. The refracted ray will bend away from it, toward the normal.

Again, the grey dotted line is the undeviated path for the light to travel. The refracted ray will bend away from it, toward the normal. 6)Draw the refracted ray. But this time, as (  i) gets larger, so does (  R).

6)Draw the refracted ray. In this case, the incident ray is along the normal (  i=0º). The light ray does not refract or bend; it travels straight through. OR  i =  R = 0º.

7)What’s wrong with these diagrams? Draw the correct refracted ray. The incident and refracted rays are always on the opposite side of the normal.

7)What’s wrong with these diagrams? Draw the correct refracted ray. The incident ray bends towards the normal and the angle of refraction ( ∠ R) is less than the angle of incidence ∠ i.

7)What’s wrong with these diagrams? Draw the correct refracted ray. The incident ray bends towards the normal, NOT away from it.

8)Draw the rays as they are refracted into glass.

The incident ray bends towards the normal. Since all incident rays are parallel, all refracted rays are parallel.

8)Draw the rays as they are refracted into glass. The incident ray bends towards the normal. Since all incident rays are parallel, all refracted rays are parallel.

8)Draw the rays as they are refracted into glass. If the circular region where the first incident ray meets the semi-circular prism is greatly magnified……

8)Draw the rays as they are refracted into glass. The curve would look like a straight line which is the same as the tangent to the semi-circle. The dotted line or radius is perpendicular to this, as would be the incident ray.

8)Draw the rays as they are refracted into glass. Therefore, the incident ray would be along the normal to the surface ( ∠ i=0) and the refracted ray would not bend ( ∠ R=0).

8)Draw the rays as they are refracted into glass. Returning to normal magnification would make the first refracted ray look like the above.  i =  R = 0º

8)Draw the rays as they are refracted into glass. The second incident ray is parallel to the first, but the tangent where it meets the prism has rotated. Therefore, there is an angle of incidence and the ray refracts or bends toward the normal (which is also the radius, in this case).

8)Draw the rays as they are refracted into glass. The third incident ray is parallel to the first, but the tangent has rotated again. The incidence ray refracts toward the normal. As (  i) gets larger, so does (  R).

8)Draw the rays as they are refracted into glass. If all incident rays are parallel, this refracted ray would be the same as those in the first diagram.

8)Draw the rays as they are refracted into glass. The last incident ray is also parallel to the first, but again, the tangent has rotated. The incidence ray still refracts toward the normal. Again, as (  i) gets larger, so does (  R).

8)Draw the rays as they are refracted into glass. All incident rays together would look like this.

9)The Angles of Refraction ( ∠ R) in Pure Water are given on the table. Some reasons that you did not get exactly the same measurements may have been: You did not align the semicircular container properly with the protractor template. You did not make sure that the ray passed through the centre of the flat surface of the semicircular container. You mistook the light which passed over the container for the light that refracted through it. The protractor template was not accurate enough. All experimental observations contain error.