"Exploring the Law of Reflection of Light" Light and Eyes PPT Courseware

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"Exploring the Law of Reflection of Light" Light and Eyes PPT Courseware

teaching objectives

1. Know what the reflection phenomenon of light is; understand the law of light reflection, and be able to apply the law of light reflection to solve some simple problems. Know that in the phenomenon of reflection, the light path is reversible.

2. Know specular reflection and diffuse reflection, and be able to use relevant knowledge to explain some simple phenomena.

3. Cultivate students’ ability to discover and research problems.

4. Understand the application of light reflection in real life.

Detection Preview Exchange Display

a. Exchange examples of light reflection phenomena in life? Understand the reflection of light, reflected light, incident light, reflection angle, and incident angle; memorize and understand the laws of light reflection. Understand that light paths are reversible.

b. What are specular reflection and diffuse reflection? The difference between the two? Give examples of specular reflection and diffuse reflection in life.

c. Application examples of light reflection.

1. Reflection of light

When light hits the surface of an object, part of the light will be reflected back by the surface of the object. This phenomenon is called reflection of light.

think about it

Is there any way to make a beam hitting the ground illuminate the wall?

Try to draw the path of light?

Research activity one

1. Terms: incident point, incident ray, reflected ray, incident angle, reflection angle

2. Activity 1: Let a beam of light hit a plane mirror at an angle of 20 degrees and measure the reflection angle; change the incident direction, measure the reflection angle, and fill in the relevant data in the table.

3. Move the direction of the incident light to coincide with.

4. Gradually move away from the overlapping position and observe the changes in reflected light.

5. Using the normal ON as the axis, slowly rotate the cardboard OB around the normal ON to find the positional relationship between the incident light, reflected light and normal.

Guess?

1. Are the reflected rays, incident rays, and normals in the same plane?

2. Are the reflected rays and incident rays located on the same side or different sides of the normal?

3. What is the relationship between the reflection angle and the incident angle?

law of reflection of light

When light is reflected, the reflected ray, incident ray and normal line are in the ______ plane; the reflected ray and the incident ray are respectively located on the normal line ______; the reflection angle _______ the incident angle.

Can light return along the same path?

In the reflection of light, the light path is reversible.

reflection of mirror

When parallel rays of light strike a smooth surface, the reflected rays of light are also parallel.

diffuse reflection

Parallel rays of light hit the uneven surface, and the reflected rays of light shoot in all directions.

Classroom training

1. When the angle between the incident light and the mirror decreases from 90º to 60º, the reflection angle ( )

A. Decrease from 90º to 30º B. Increase from 30º to 90º

C. Decrease from 30º to 0º D. Increase from 0º to 30º

2. Supplement the following picture

3. Draw the reflected light path

4. Use a plane mirror to change the light path

(1) A beam of light is incident at an angle of 40° to the horizontal plane. In order for it to be reflected by a plane mirror and then emitted horizontally, how should the plane mirror be placed?

5. The angle between the incident light and the mirror is 30º. If the mirror is rotated 15º, the angle between the reflected light and the incident light is___________.

6. Why do the chalk characters become unclear when the blackboard is "reflective"?

Because light will be reflected when it hits the blackboard and chalk characters. Specular reflection occurs on the "reflective" part of the blackboard, and diffuse reflection occurs on the words. When the reflected light from the two parts of the blackboard hits the eyes at the same time, the reflected light from the specular surface is stronger than the diffusely reflected light, which causes strong irritation to the eyes. Therefore, when the blackboard is "reflective", the chalk writing becomes unclear.

Try your hand

Optical fiber communication is an important method of modern communication. The inner wall of the optical fiber has the property of reflecting light, so that the light incident from one end can propagate to the other end of the optical fiber. Please draw a light path diagram in Figure 13 to show the principle of optical fiber transmission of optical signals.

Operation:

Classwork: Questions 1, 2, 3, 4, 5, and 6 on page p55.

Tutorial (preview):

a. Give examples of plane mirror imaging phenomena in life.

b. What are the characteristics of plane mirror imaging?

c. What are the applications of plane mirror imaging in daily life?

d. What are the characteristics and applications of convex mirrors and concave mirrors in daily life?

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"Exploring the Law of Reflection of Light" Light and Eyes PPT Courseware 2:

"Exploring the Law of Reflection of Light" Light and Eyes PPT Courseware 2 Learning Objectives 1. Know what the reflection phenomenon of light is 2. Understand the law of reflection of light and the reversibility of the light path in the reflection phenomenon 3. Know specular reflection and diffuse reflection, and It can be used to analyze the core of some simple phenomena...

File Info

Update Time: 2024-10-19

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

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