Bell Ringer #9 Thursday, November 16, 2017 What causes light rays to bend? When light rays enter a new medium at an angle, the change in speed causes the rays to bend. What determines the type of image formed by a lens? It depends on the shape of the lens and the position of the object. A Concave lens is thinner in the center and light rays bend away from the optical axis. The image appears smaller than the object. A Convex lens is the opposite.

REVIEW YESTERDAYS WORKSHEET REFLECTIONS AND MIRRORS

Unit 4 – Wave Behaviors and EM Waves Chapter 4 – Light Lesson 3 – Refraction and Lenses (Pages 128 - 135)

SCCCR Standards 8.P.3: The student will demonstrate an understanding of the properties and behaviors of waves. 8.P.3A. Waves (including sound and seismic waves, waves on water, and light waves) have energy and transfer energy when they interact with matter. Waves are a repeating pattern of motion that transfers energy from place to place without overall displacement of matter. All types of waves have some features in common. When waves interact, they superimpose upon or interfere with each other resulting in changes to the amplitude. Major modern technologies are based on waves and their interactions with matter. 8.P.3A.3 Analyze and interpret data to describe the behavior of waves (including refraction, reflection, transmission, and absorption) as they interact with various materials. 8.P.3A.5 Construct explanations for how humans see color as a result of the transmission, absorption, and reflection of light waves by various materials. 

SCCCR Science and Engineering Practices 8.S.1: The student will use the science and engineering practices, including the processes and skills of scientific inquiry, to develop understandings of science content. 8.S.1A. The practices of science and engineering support the development of science concepts, develop the habits of mind that are necessary for scientific thinking, and allow students to engage in science in ways that are similar to those used by scientists and engineers. 8.S.1A.4 Analyze and interpret data from informational texts, observations, measurements, or investigations using a range of methods (such as tabulation, graphing, or statistical analysis) to (1) reveal patterns and construct meaning or (2) support hypotheses, explanations, claims, or designs. 8.S.1A.5 Use mathematical and computational thinking to (1) use and manipulate appropriate metric units, (2) collect and analyze data, (3) express relationships between variables for models and investigations, or (4) use grade-level appropriate statistics to analyze data.

What causes light rays to bend? Essential Questions What causes light rays to bend? What determines the type of image formed by a lens?

Vocabulary Index of refraction A measure of the amount a ray of light bends when it passes from one medium to another Mirage An image of a distant object caused by refraction of light as it travels through air of varying temperature Lens A flexible structure that focuses light that has entered the eye A curved piece of glass or other transparent material that is used to refract light

Vocabulary Concave lens A lens that is thinner in the center than at the edges Convex lens A lens that is thicker in the center than at the edges

Check out figure 1 on page 129. There is only one fish in the tank. Why do you see two? Light rays speed up or slow down when they pass from one medium to another. Both side of glass have refracted the image. Also, objects look bigger in water than they really are for the same reason.

DO THE MATH , page 130 Refraction in different mediums. Some mediums bend light more than others. What has a higher refractive index; air, water or glass? Glass has the highest (light bends the most) Water is next and (light bends a little less) Air has the lowest (light bends the least). DO THE MATH , page 130

Prisms and Rainbows Remember, white light is made up of all colors of light. When white light enters a prism, each color is refracted by a different amount producing the colors of the rainbow. That is, each color has a different wavelength so each color is refracted differently. Water droplets are like tiny prisms which causes a rainbow to form.

Describe the shape of a concave lens. Thinner in middle What type of image does a concave lens produce? A virtual image What is the size and position of the image? Smaller and upright

What type of lens is this? Concave What happens to light rays as they pass through? The are refracted How do the paths of the light rays change? They spread apart How many time is a light ray refracted? 2 Object image Focal point

Look at figure 6 on Page 134 in your text book. What kind of image is this? Virtual How can you tell? It is upright What type of lens is being used? Explain. A convex lens- it enlarges the image HOWEVER- a convex lens can have more than one type of image What is the shape of a convex lens? Thicker in the middle How does this differ from a concave lens?

Look at figure 7 on page 134. How does the lens affect the direction of light rays when the object is beyond the focal point? It bends the rays towards each other How does the lens affect the direction of light rays iwhen the object is between the focal point and the lens? It bends the light rays away from each other Which diagram shows what is happening in figure 6 above? The lower diagram- the object is between the focal point and the lens.