Unit 2 Ls 2 Role of Animals’ eyes (M2).pptx

Light properties and role of animals' eyes

1. Role of Animals’ eyes

2. Reflection – What is it ? Reflection is the bouncing of light waves off a surface. Example of Reflection .

3. Reflections – What is the most and the least ? The Most - Smooth, shiny surfaces such as mirror can reflect the most. The Least - Dull, rough surfaces reflect the least amount of light.

4. Reflection – How does it work ? When light reflects off a surface, it changes direction Source of light The light rays moving towards a surface are the incoming rays. And the reflected light rays are the outgoing rays. The angels of the incoming rays and outgoing rays are always equal. This is called the Law of Reflection.

5. The image you see in the mirror is a picture of the light source that light rays make when bounced off a polished, shiny surface.

6. Refraction – What is it ? Refraction is the bending of a light wave as it changes angles passing from one substance into another. Light slows down when it moves from one material to a denser material. This decreases in speed causes the light’s angle to change, or its direction to bend.

7. Example of Refraction Fish appears here Fish is here

8. Lens A clear piece of glass or plastic through which light travels is called a lens.

9. Types of lens Flat Lens If the lens is flat, the light’s path shifts a little, but it’s final direction does not change. Flat lens

10. Concave lens A lens that is thinner in the middle is a concave lens. Light that passes through a concave lens spread outwards. Concave lens

11. Convex lens A lens that is thicker in the middle is a convex lens. A light that passes through a convex lens will come together at a focus point The image you see when you look at an object through a convex lens depends on how far away the object is. Up close, the lens will cause the object to look bigger. Far away, the image will appear upside down and smaller.

12. The Human Eye You see an image when light reflects off an object and enters your eye. The eye receives upside down images.

13. Transparent, Translucent and Opaque Transparent: Materials that let light through, so objects on the other side can be seen clearly are called transparent. Translucent: Materials that let some light pass through, so objects on the other side appear blurry are called translucent. Opaque: Materials that block light from passing though are called opaque.

14. The Way Eyes See It Depending on where and how animals live, they all have different types of eyes. One thing is for sure, they use light in different ways to survive in the wild. Some animals have eyes on the front of the head, while others have it on their sides. Frogs, for instance, have eyes on top of their heads. Other animal eyes can see many colours, but there are some that see only black, white and grey.

15. Chameleon Frog Fish

16. How Animals Use Their Eyes Predators usually have their eyes on the front of their head, which helps them to see far away objects, aiding in the hunting of other animals. Preys (animals that predators eat) have eyes on the side of their heads which help them to see dangers around them. Lions have reflectors in their eyes that help them see at night. This makes them appear glow

17. Fishes are another group of animals that have eyes present on their sides. These eyes contain special structures that allow fish to see underwater movement, which helps them to see their predators and escape them. Moreover, it helps fish to catch prey.

18. Dragonflies, bees and other insects have compound eyes. These two giant-bubble like structures have thousands of small lenses inside of them which all them to see all directions. Owls have eyes that are 100x more sensitive to low light than human eyes which allows them the ability to see prey at night. In a case of an eagle, objects appear larger than what humans see which allows them to see prey from far distances.