"Exploring the Law of Refraction of Light" Light and Eyes PPT Courseware 2

Description

"Exploring the Law of Refraction of Light" Light and Eyes PPT Courseware 2

learning target

1. Know what the refraction of light is

2. Know the laws of refraction of light

3. Know that when light is refracted, the light path is also reversible.

4. Through observation, experience the illusion caused by refraction and initially appreciate the beauty of the refraction phenomenon.

Core test points: Application and drawing of refraction phenomena

Preview before class

1. The phenomenon of refraction of light: When light ______ from one medium to another medium, the direction of propagation is deflected. This phenomenon is called refraction of light.

2. The law of refraction: When light is incident from air into water, glass and other transparent substances, the refracted light is deflected in the direction of the normal line of _______; when light is incident from water, glass and other transparent substances into the air, the refracted light is deflected in the direction of _______ _The direction of the normal is deflected.

3. From the figure below, we can see that ___________ is the interface, __________ is the incident light, _______ reflects the light, the incident angle is _______ degrees, the refraction angle is ______ degrees, and the reflection angle is _______ degrees.

Lectures in class

Knowledge point 1. The phenomenon of refraction of light

When light is incident obliquely from one medium into another medium, the direction of propagation changes. This phenomenon is called refraction of light.

Note: The refraction phenomenon occurs at the interface of two media, such as water and air, water and glass, etc., and enters another medium. The propagation direction changes during oblique incidence as shown in Figure A below. The propagation direction remains unchanged during vertical incidence. , as shown in Figure B below. Reflection and refraction occur at the interface of the medium at the same time, that is, an incident light is divided into two parts, one part is reflected back to the original medium; one part enters another medium after refraction. The reason for the refraction phenomenon is Light propagates at different speeds in different media.

Knowledge point 2. The law of refraction of light

When light is refracted, the refracted ray, incident ray and normal line are in the same plane, and the refracted ray and incident ray are located on both sides of the normal line respectively. The refraction angle changes with the change of the angle of incidence: when the angle of incidence increases, the angle of refraction also increases; when the angle of incidence decreases, the angle of refraction also decreases.

When light is incident obliquely from air into water or glass, the refraction angle is smaller than the incident angle; when light is incident obliquely into air from a medium such as water or glass, the refraction angle is greater than the incident angle. When learning the law of refraction of light, we should focus on understanding it from the three perspectives of "three lines", "two angles" and "one side", as shown in the table below.

[Example 3] (2014·Jining) Last summer vacation, Xiaomeng accompanied her grandfather to the lake to spear fish. Xiaomeng threw the steel fork in the direction of the fish he saw, but he always failed to reach the fish. Among the four light path diagrams shown below, the reason why the fish cannot be caught is ( )

[Exercise 3] (2014·Yunnan) When driving on the road in the hot summer, I often feel that there is water in the distance of the road, and there are reflections of cars, poles and other objects in the water. However, when the car drives there, the water disappears. Disappeared. This phenomenon occurs because of light ( )

A. Diffuse reflection b. Specular reflection C. refraction d. straight line propagation

Knowledge point 4. Similarities and differences between light refraction and light reflection

(1) Similar points:

① When light propagates to the interface of two media, reflection and refraction generally occur at the same time.

② Both reflected rays and refracted rays are in the same plane as the corresponding incident rays and normals, and both are separated from the incident rays on both sides of the normal.

③Both the reflection angle and the incident angle increase (decrease) as the incident angle increases (decreases).

④The light path is reversible during reflection and refraction.

(2) Differences:

① Reflected rays and incident rays are in the same medium, while refracted rays and incident rays are in different media.

②The reflection angle is always equal to the incident angle, and the refraction angle is equal to the incident angle only when the incident is vertical.

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"Exploring the Law of Refraction of Light" PPT courseware on light and eyes:

"Exploring the Laws of Refraction of Light" Light and Eyes PPT Courseware Teaching Objectives 1. Understand the phenomenon of refraction of light. 2. Understand the laws of refraction of light and be able to use the laws to analyze and explain common refraction phenomena in life. 3. Experience experiments to explore the regular process of refraction of light, and cultivate general...

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Update Time: 2024-09-08

This template belongs to Physics courseware Guangdong and Shanghai version of eighth grade physics volume one industry PPT template

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