Kneel and beg for the final exam questions of the eighth grade physics volume I of People's Education Edition.

①

1. Definition: When light is emitted from one medium to the surface of another medium, part of the light is reflected back to the original medium, which is called optics? Reflection.

2. Reflection law: three lines are coplanar, the normal is centered, the two angles are equal, and the optical path is reversible. That is to say, in the phenomenon of light reflection, reflected light? In the same plane of incident light and normal, reflected light and incident light are separated on both sides of normal, and the reflection angle is equal to incident light? Horn. The light path is reversible in the process of light reflection. An unlit object will reflect the light that shines on it into our eyes.

3. Classification:

(1) specular reflection:

Definition: parallel light incident on the surface of an object is still parallel after reflection.

Condition: The reflecting surface is smooth.

Application: looking at the calm water facing the sun, it is particularly bright. The blackboard "reflects light" and so on, all because of specular reflection.

(2) Diffuse reflection:

Definition: parallel light incident on the surface of an object reflects in different directions? Every ray obeys the law of light reflection.

Condition: The reflecting surface is uneven.

Application: You can see non-luminous objects from all directions, because light will diffuse when it hits an object.

Third, plane mirror imaging.

1, flat mirror:

Imaging characteristics: equal, equidistant, vertical, virtual image

(1) like, equal size.

② The distance between the image and the object and the mirror is equal.

③ The line between the image and the object is perpendicular to the mirror.

The image of an object in a plane mirror is an image.

Imaging principle: the reflection theorem of light; Function: imaging, Change the light path.

Real image and virtual image:

Real image: the image formed by the convergence point of actual light; Images can be displayed on a light screen.

Virtual image: an image formed by the convergence point of the reverse extension line of reflected light.

2. Spherical mirror:

Definition: Use the inner surface of the sphere as the reflecting surface.

Concave mirror? Nature:? Concave mirror can converge the parallel rays directed at it at one point; ? The reflected light from the focal point to concave mirror is parallel light.

Applications: solar cookers, flashlights, car headlights.

Definition: Use the outer surface of the sphere as the reflecting surface.

Convex mirror? Properties: Convex mirror diverges light. The image formed by convex mirror is a reduced virtual image.

Application: automobile rearview mirror

Fourth, the refraction of light

1. Refraction: When light is obliquely incident from one medium to another, the propagation direction is deflected, which is called light refraction. ? When refraction occurs, reflection must also occur. When light strikes the interface between two substances vertically, what is the propagation direction? there will be no changes.

2. The law of refraction of light: In refraction, refracted light, incident light and normal are all in the same plane; Light in the air? When gas is obliquely incident into water or other media, the refracted light is deflected to the normal direction (incident angle of refraction angle)? . In refraction? The light path is reversible. In the refraction of light, the refraction angle increases with the increase of incident angle. In the refraction of light? The smaller the density of the medium, the greater the speed of light and the greater the angle with the normal.

3. Refraction phenomenon: ① From the shore to the water, the water looks shallow, but it can't diverge along the direction of watching the fish; From the water? Looking at the things on the shore, it seems to be getting higher. Chopsticks seem to "fold" in water. ③ A mirage. 4 rainbow.

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The optical path diagram of fish N in the water from the shore (Figure 1)? :? The n point in the picture is the real position of the fish, and the n' point is what we see? As can be seen from the picture, the fish we see is higher than the actual position. Is the image point the opposite extension of two refracted rays? The intersection of. When the refracted optical path diagram is completed, a light perpendicular to the interface of the medium can be drawn, which is convenient for drawing

Verb (abbreviation for verb) light scattering

1. Dispersion of light: Dispersion of light belongs to refraction of light. 1666, the British physicist Newton made Thai? The sunlight is dispersed (Figure 2)? . After the sunlight passes through the prism, it is decomposed into various colors of light, which is received by the white screen. Red, orange, yellow, green, blue, indigo and purple ribbons are formed on the white screen. Newton's experiment shows that white light? It is a mixture of colors and light.

2. The three primary colors of colored light: red, green and blue. Red, green and blue light, mixed in different proportions, can produce various colors? Color light. ? (Figure 3)

Dispersive color of light, three primary colors of light and three primary colors of pigment.

Figure 2? Figure 3? 3. Color of the object: The color of a transparent object is determined by the colored light passing through it. As shown in figure 4, if one piece is placed in front of a white screen? Red glass, the light of other colors on the white screen disappears, leaving only red. Does this mean that all other colors of light are absorbed by red glass? Well, only red light can pass through. The color of an opaque object is determined by the colored light it reflects. As shown in figure 4, if you put one? If you stick green paper on a white screen, there is no ribbon on the green paper, and only the place where green light shines is bright (reflecting green light)? ,? Other places are darker (not reflective)? . If an object can reflect all colors of light, it looks white. If one? An object can absorb all colors of light, so it appears black. If an object can transmit all colors of light, it is nothing. Transparent color.

Chapter five? Lens and its application? First of all, the lens

1, noun

Thin lens: the thickness of the lens is much smaller than the radius of the sphere.

Principal optical axis: a straight line passing through the centers of two spherical surfaces.

Take it easy: (o) the center of the thin lens. Property: the direction of light propagation through the optical center is unchanged.

Point (f)? A convex lens can make light parallel to the main optical axis converge at a point on the main optical axis, which is called focus.

Focal length (f)? Distance from focal point to optical center of convex lens.

Difference: convex lens: thick in the middle and thin on both sides; Concave lens: thin in the middle and thick on both sides.

Red? purple

ordinary

water

air

O

water

Air? O

ordinary

Figure 1

Angle of reflection

Angle of refraction? refraction angle

Angle of reflection

Color of transparent object

The color of an opaque object.

Red? sunlight

green

Figure 4

sunlight

Red glass? White screen? Green Book

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2. Typical optical path

3. fill in the form: Name? Also known as? Glasses? Body shape? Optical symbol? Natural? Convex lens? Convergent lens? Reading glasses? Have a converging effect on light? Concave lens? Divergent lens? Close-up? It has a divergent effect on light.

Second, the lens in life? Camera? Projector? amplifier

Principle? Convex lens imaging? u>2f？ f； 2f。 Adjust the distance from _ _ _ _ _ _ _ to the convex lens to make the candle flame on the screen.

Form a clear image and observe the essence of the image;

(3) Then change the object distance respectively, repeat the above operations, and observe the imaging situation;

④ Summarize the following conclusions. Please fill in the form completely.

(2) When Xiao Yu explored the experiment of boiling water, she got the following data:

As can be seen from the above table, the boiling point of water is _ _ _ _ _ _ _ _℃. During the boiling process, it is observed that water will be heated continuously, but the temperature will not change.

(3) In the experiment of exploring the imaging characteristics of flat mirror, Ye moved the candle behind the glass plate and put a light screen in its place, and found that the image of candle A in front of the glass plate could not be received on the light screen. Experiments show that the image formed by a flat mirror is _ _ _ _ _ _ _.

26.(3 points) The picture shows a simplified circuit diagram of a refrigerator. After learning the knowledge of series-parallel circuit, can you understand this circuit diagram? Where m is the motor of the compressor and l is the light bulb in the refrigerator. Are the bulb L and the motor M connected in series or parallel in the circuit diagram? Please write down your guess and judgment.

Guess: .

Judgment method:

27.(6 points) Explore the factors that affect the evaporation rate of liquid.

Question: What factors are related to the evaporation rate of liquid?

Conjecture and Hypothesis Conjecture 1: The evaporation rate of liquid may be related to liquid? Height, liquid? The size of the liquid and the surface of the air

The flow rate is related.

Conjecture 2: Under the same conditions, rubbing water and alcohol on the arm at the same time makes alcohol easier to dry, so it is speculated that the evaporation rate of liquid may be static.

With what? About.

Design and experiment Xiaoming did the following experiment on one of the conjectures:

As shown in the figure, drop a drop of alcohol with the same quality on two identical glass plates. By observing the scene in the picture,

He explored whether the speed of alcohol evaporation was related to it.

Do you need to control alcohol during the experiment? As fast as air flows on its surface.

Communication and evaluation?

We know that liquid absorbs heat when it evaporates. Please give an example of using evaporation to absorb heat.

Example:.

28.(6 points) In order to explore the current law in parallel circuits, please:

(1) In the experiment, besides the power supply, several wires and switches, other equipment is needed.

what's up 、 ? (Please write down the number of equipment required)

(2) Draw the experimental circuit diagram in the box.

(3) Design a table to record the experimental data.

answer

First, multiple choice questions

123456789 10 1 1 12

ADDCCAACBDAB

Second, fill in the blanks

13, convex? Myopia? Concave infiltration

14, sublimation? sublimate

15、0? 100? 37? —3? 1 1 37.5

16, crystal? 45? 15? Absorption of heat

17, vaporization endothermic (or vaporization endothermic)? ; ? Liquefaction exotherm

18, sound can transmit energy.

19, I can't hear it. It's getting bigger.

20. Maybe?

2 1, (1) The filament of the bulb is broken or the contact is poor.

(2) The battery is dead or the battery is installed backwards. As long as it is reasonable, you can give points.

22. in series? Extinguish 1

Three. (1) Omit (2) The answer is shown in figure 1 (2 points). (The incident light, refracted light and its reverse extension lines get 1 minute respectively. If the reverse extension line of refracted light is not drawn, or the reverse extension line of refracted light is not on B'C, the light is not marked with an arrow or the direction of the arrow is reversed, or the light is drawn with a dotted line, all scores are 0).

Fourth, the experimental questions

24.( 1) Liquid expands when heated and contracts when cooled;

(2) Different scope? ; Different segmentation values; There is a contraction on the thermometer, and so on.

Scoring comments: 1 point * * * 3 points for each answer. All other reasonable answers are given for reference.

② When reading, the line of sight is not in a straight line with the mercury column in the thermometer.

(2) Liquefied water droplets will release heat when liquid is liquefied.

25. Answer: (1)① Same height? ② Light screen ④ Camera 2f>u>f is standing?

(2) 100 suction (3) insufficient

26. Guess: Parallel connection mode: When you can't hear the motor compression sound, open the first frost door and see if the light is on.

27. Conjecture 1: Temperature? superficial area

Conjecture 2: Matter

Design and conduct the surface area temperature of the experimental liquid.

Exchange and evaluate the cooling of ground sprinkling in summer.

Rating comments: 1 each space, ***6 spaces. Please refer to the score for other reasonable answers.

28.⑴? One meter and two resistors (or lamps).

⑵? (omitted)

⑶?

The current through L 1 I 1? /Current I2 through L2? /A main current I/A