The first chapter "sound phenomenon" review overview.

First, the occurrence and spread of sound.

1. Everything that makes a sound is vibrating. The vibration stops and the sound stops. Sound source of vibrating object.

2. The spread of sound needs media. The media that transmit sound include solid, liquid and gas, and vacuum cannot transmit sound.

3. Sound spreads outward in the form of sound waves.

4. The speed of sound propagation in the medium is simply called the speed of sound. At 15℃, the speed of sound propagation in air is 340 m/s, which is the slowest in air, faster in liquid and fastest in solid.

5. Echo is formed because the sound meets obstacles and is reflected back in the process of propagation.

Second, how do we hear the sound?

1, the way of sound propagation in the ear: the external sound causes the tympanic membrane to vibrate, and this vibration is transmitted to the auditory nerve through the ossicles and other tissues, and the auditory nerve transmits the signal to the brain, and people hear the sound.

2. Deafness: divided into nerve deafness and conductive deafness.

3, bone conduction: sound can be transmitted not only through the ear, but also through the skull and jaw to the auditory nerve, causing hearing. This mode of sound transmission is called bone conduction. Some people who have lost their hearing can hear sound in this way.

4. Binaural effect: People have two ears, not one. The distance from the sound source to the two ears is generally different, and the time and intensity of sound reaching the two ears are also different. These differences are an important basis for judging the direction of sound source. This is the binaural effect.

Third, the sound of music and its three characteristics

1. Music is the sound made when an object vibrates regularly.

2. Tone: The level of sound that people feel. Tone is related to the vibration frequency of the vocal body, and the higher the frequency, the higher the tone; The lower the frequency, the lower the pitch. The number of times an object vibrates at 1s is called frequency. The faster an object vibrates, the higher its frequency. The frequency range that most people can hear is 20Hz to 20000Hz. The sound above 20000Hz is called ultrasonic wave, and the sound below 20Hz is called infrasound.

3. Loudness: the volume of sound felt by the human ear. Loudness is related to the amplitude of the generator and the distance from it. When an object vibrates, the maximum distance from its original position is called amplitude. The greater the amplitude, the greater the loudness.

4. Tone: It is determined by the object itself. People can distinguish musical instruments or people according to their timbre.

Fourth, the harm and control of noise

1. Four major pollutions in contemporary society: noise pollution, water pollution, air pollution and solid waste pollution.

2. From the physical point of view, noise refers to the sound produced when the vocal body vibrates irregularly and disorderly; Environmental protection angle noise refers to the sound that interferes with people's normal rest, study and work and the sound that people want to hear.

People use decibels (dB) to divide the sound level.

4. Ways to reduce noise: at the sound source, in the process of propagation, at the human ear.

Verb (abbreviation of verb) the use of sound

Sound can be used to spread information and transmit energy.

Chapter II Overview of Light Phenomenon

First, the straight-line propagation of light

Light source: An object that can emit light is called a light source. It is divided into natural light source and artificial light source.

1, the propagation of light

① Propagation Law: Light propagates in a straight line in the same uniform medium.

② Light: In order to represent the propagation of light, we usually use straight lines with arrows to represent the trajectory and direction of light. Such a straight line is called light.

③ Application and phenomenon: A laser collimates B shadow to form C solar eclipse and D pinhole imaging.

2. the speed of light

In vacuum or air, c = 3×108m/s = 3×105km/s.

Water is 3/4 of that in a vacuum. Glass is two-thirds of that in a vacuum. 1 light year =9.46× 10 12km.

Second, the reflection of light.

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 light reflection.

2. Law of reflection: reflected light is in the same plane as incident light and normal; Reflected light and incident light are separated on both sides of the normal; The reflection angle is equal to the incident angle.

The light path is reversible in the process of light reflection.

3, the classification of reflection:

⑴ Specular reflection-parallel light incident on a smooth surface is still parallel after reflection.

⑵ Diffuse reflection-parallel light incident on uneven surface reflects in different directions, and each beam obeys the law of light reflection.

Third, plane mirror imaging.

1, imaging characteristics of plane mirror

① The size of the image and the object are equal; 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 a virtual image. (Images and objects are symmetrical about a mirror)

Imaging principle: reflection theorem of light

2. Real image and virtual image:

Real image: the image formed by the convergence point of actual light.

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

Fourth, the refraction of light

1, refraction phenomenon

When light is obliquely incident from one medium to another, the propagation direction is deflected, which is called light refraction.

2. Refraction law: refracted light is in the same plane as incident light and normal; Refracted light and incident light are separated on both sides of the normal; When light obliquely enters water or other media from air, the refraction angle is smaller than the incident angle, and when light obliquely enters air from water or other media, the refraction angle is larger than the incident angle (compared with water, air and glass, the angle is larger in the media with faster propagation speed).

The light path is reversible when refracted.

Verb (abbreviation for verb) light scattering

1. Composition of white light: red, orange, yellow, green, blue, indigo and purple.

2. The three primary colors of colored light: red, green and blue.

3, the color of the object:

The color of transparent body is determined by the colored light passing through it.

Opaque color: determined by the reflected color light.

6. Invisible light

1. spectrum: arrange red, orange, yellow, green, blue, indigo and violet light in this order, which is the spectrum.

2. Invisible light: infrared and ultraviolet rays.

★ We can see luminous objects because the light emitted by the objects enters the eyes.

★ We can see objects that don't emit light because the light reflected by the objects enters the eyes.

Chapter III Overview of Lenses and Their Applications

First of all, the lens

1, classification: convex lens, concave lens

Convex lens: thick in the middle and thin in the edge. Like reading glasses.

Concave lens: thin in the middle and thick in the edge. Such as: myopia glasses.

2. Nouns:

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

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

3. The influence of lens on light

A convex lens has a convergent effect on light, while a concave lens has a divergent effect on light.

4. Focus and focal length

Focus (f): The point on the main optical axis where the convex lens can converge the light parallel to the main optical axis is called focus.

Focal length (f): the distance from the focal point to the optical center of the convex lens.

Second, the lens in life

Camera, projector, magnifying glass: the lens is equivalent to a convex lens.

Camera: an inverted and reduced real image.

Projector: a real image magnified in an inverted manner.

Magnifier; Into an upright enlarged virtual image.

Thirdly, explore the imaging law of convex lens.

Convex lens imaging rule table and optical path diagram;

Application of object distance reverse scaling method in virtual and real image distance

Inversion reduction of u & gt2f real image F

U=2f, inverted image v=2f.

F<u< Real Image 2f Inverted Amplification v & gt2f Projector and Slide Show Machine

U=f no image

U<F |v| > magnifying glass

Overview of convex lens imaging;

① Two cut-off points: the cut-off point between real image and virtual image: focus, and the cut-off point between enlarged image and reduced image: double focal length.

② When the object approaches the focus of the convex lens from a distance, the object distance decreases, the image distance increases and the real image increases; When the object approaches the focus from the lens, the virtual image becomes bigger and bigger.

③ The difference between real image and virtual image: the real image is the intersection point of actual light convergence, and the virtual image is the intersection point of the reverse extension line of light.

Four, eyes and glasses

Eyes: the eyeball is like a camera, the lens and cornea are equivalent to convex lenses, and the retina is equivalent to a light screen.

Correction of myopia and hyperopia: wear concave lenses for myopia and convex lenses for hyperopia.

Verb (abbreviation for verb) microscope and telescope

1 microscope

The convex lens is used as an objective lens and the convex lens is used as an eyepiece. The focal length of the objective lens is very short. The object distance is greater than the focal length of the objective lens and less than twice the focal length of the objective lens. The light emitted by the observed object forms an inverted magnified real image through the objective lens, which is equivalent to an object relative to the eyepiece, and the object distance from the eyepiece is smaller than the focal length of the eyepiece, which is equivalent to a magnifying glass, and the image is magnified again.

2. Telescope

Kepler telescope (mentioned in the textbook): convex lens for objective lens and convex lens for eyepiece. The back focus of the objective lens coincides with the front focus of the eyepiece. The object distance is more than twice the focal length of the objective lens, and the light emitted by the observed object passes through the objective lens, forming an inverted reduced real image near the focal length of the objective lens. The real image is equivalent to an object relative to the eyepiece, and the object distance relative to the eyepiece is smaller than the focal length of the eyepiece. The eyepiece is equivalent to a magnifying glass, which magnifies the real image.

Galileo telescope: The convex lens is used as the objective lens and the concave lens is used as the eyepiece.

The diameter of the telescope objective lens is larger, which can gather more light and make the image brighter.

Angle of view: the angle of view formed by an object to the eyes is not only related to the size of the object itself, but also related to the distance from the object to the eyes. The larger the viewing angle of an object to the eye, the larger the object the eye sees.

The fourth chapter "the change of state" reviews the outline.

I. Temperature

1, definition: temperature indicates the degree of heat and cold of an object.

2. Unit:

(1) the international system of units adopts thermodynamic temperature, and the unit is K ..

② The commonly used unit is Celsius (℃). It is stipulated that the temperature of ice-water mixture at standard atmospheric pressure is 0 degrees, and the temperature of boiling water is 100 degrees. They are divided into equal parts of 100, and each part is called 1 degree Celsius. The temperature in a place is -3℃, which is pronounced as -3℃ or -3℃.

③ conversion relation T=t+273K

3, measurement-thermometer (commonly used liquid thermometer)

(1) Thermometer principle: It works by using the principle that liquid expands when heated and contracts when cooled.

② Classification comparison:

Classified experimental thermometer

Objective to measure the temperature, room temperature and body temperature of objects.

The range is-20℃ ~110℃ ~ 30℃ ~ 50℃ and 35℃ ~ 42℃

The dividing value is 1℃ 1℃ 0. 1℃

Liquid mercury kerosene (red) alcohol (red) uses mercury.

There is a special structure necking above the glass bulb.

Usage: Do not shake when using, and do not leave the reading of the object when measuring. Shake it before use, and you can leave the reading of human body.

(3) The use of common thermometers:

Before use: observe its range and judge whether it is suitable for the temperature of the measured object; And identify the scale value of the thermometer for accurate reading. When in use: all the glass bubbles of the thermometer are immersed in the liquid to be measured, and do not touch the bottom or wall of the container; Immerse the glass bulb of the thermometer in the liquid to be measured for a while, and then read after the pointer of the thermometer is stable; When reading, the glass bubble should stay in the liquid to be measured, and the line of sight should be flush with the upper surface of the liquid column in the thermometer.

Second, melting and solidification.

① Three states of matter: solid, liquid and gas.

② Melting:

Definition: The change from solid to liquid is called melting. Melting absorbs heat.

Melting point: The temperature at which the crystal melts is called the melting point of the crystal. Different crystals usually have different melting points.

Solids are divided into crystalline and amorphous. The main difference between them is that the crystal has a certain melting point, but the crystal does not.

Crystal substances: hypo, ice, seasonable, crystal, salt, alum, sodium chloride, various metals, amorphous substances: rosin, paraffin, glass, asphalt and beeswax.

Melting image:

③ curing:

Definition: The change from liquid to solid is called solidification. Solidification exothermic.

Freezing point: The temperature at which crystals solidify is called freezing point. The same crystal has the same freezing point and melting point.

Solidification image:

Third, vaporization and liquefaction:

(1) vaporization-the change of a substance from a liquid to a gas is called vaporization. There are two ways of vaporization: evaporation and boiling. Vaporization absorbs heat.

Boiling: At a certain temperature, the inside and surface of a liquid undergo intense vaporization at the same time.

Boiling point: the temperature at which a liquid boils. The boiling points of different liquids are generally different. The boiling point of water is 100℃.

Boiling condition: (1) reaches the boiling point. (2) Continue to absorb heat.

Relationship between boiling point and air pressure: The boiling point of all liquids decreases when the air pressure decreases and increases when the air pressure increases.

Evaporation: at any temperature, the liquid only evaporates slowly on the surface of the liquid.

Factors affecting evaporation rate: (1) liquid temperature; (2) the surface area of the liquid (3) the airflow on the surface of the liquid.

Function: Evaporation absorbs heat (absorbing external or self heat) and has refrigeration function.

(2) Liquefaction: The process of changing a substance from a gaseous state to a liquid state is called liquefaction. Liquefaction exothermic.

Methods: (1) Reduce the temperature; (2) compression volume.

Fourth, sublimation and sublimation:

① Sublimation: The process that a substance directly changes from a solid state to a gas state. Sublimation absorbs heat, and substances that are easy to sublimate are iodine, ice, dry ice, camphor and tungsten.

② Sublimation: The process that a substance directly changes from a gaseous state to a solid state and releases heat by sublimation.

Chapter V Review Outline of Current and Circuit

First of all, charge

1, charge

(1) charged (charged): The rubbed object has the property that light and small objects attract objects, so we say that the object is charged (charged).

② Frictional electrification: the phenomenon that the rubbed object attracts light and small objects.

③ Two kinds of charges: There are only two kinds of charges in nature.

Positive charge: the electricity carried by rubbing a glass rod with silk.

Negative charge: the electricity carried by fur rubbing rubber rod.

(4) Law of charge interaction: like charges repel and different charges attract. Application: electroscope

⑤ Charge amount: The charge amount is called charge amount, or simply charge. Unit: Coulomb (Celsius)

2. Atomic structure of original charge

Atomic structure: Atoms consist of positively charged nuclei and negatively charged electrons, which move around the nuclei at high speed. Usually, the positive charge of the nucleus is equal to the negative charge of all electrons outside the nucleus, and the whole atom is neutral, that is, the atom is not charged externally.

People call the minimum cost the main cost. 1e =1.6×10-19c, and the charge of any charged body is an integer multiple of e.

3. The charge moves directionally in the conductor.

An object that is good at conducting electricity is called a conductor. Common conductors are: metal, graphite, human body, earth, acid-base solution, etc.

Objects that are not good at conducting electricity are called insulators. Common insulators are rubber, glass, ceramics, plastics and oil.

4. The nature of triboelectrification

The essence of triboelectrification is the transfer of electrons from one object to another. Different objects have different abilities to bind electrons. In the process of triboelectrification, the object with weak electron binding capacity has excess positive charge due to the loss of electrons, while the object with strong electron binding capacity has negative charge due to the gain of electrons. The charges carried by two objects are the same amount of heterogeneous charges, and the total amount of charges has not changed.

Second, the current and circuit

1, currently

Formation: The directional movement of electric charge forms an electric current.

Direction: The direction of positive charge movement is defined as the direction of current.

2, the composition of the circuit

Connect the power supply, electrical appliances and switches with wires to form a circuit. Only when the circuit is closed will there be current in the circuit.

3. Circuit diagram: A diagram showing circuit connections with specific symbols is called a circuit diagram.

4. Three kinds of circuits: ① path ② open circuit ③ short circuit.

Three, series and parallel connection

1. Series circuit: A circuit that connects elements one after another.

2. Parallel circuit: a circuit that connects elements in parallel.

3. Common methods for identifying series-parallel circuits: (Choose appropriate methods and master them skillfully)

① current analysis method: when identifying the circuit, the current is: positive power supply → all electrical appliances → negative power supply; If there is no shunt on the way, the electrical appliances are connected in series; If the current is shunted somewhere, each branch has only one electrical appliance, which is connected in parallel; If there is more than one electrical appliance in each branch, then there are two kinds of circuits, series and parallel, which are called series-parallel circuits.

(2) disconnection method: remove any electrical appliance, and if the other electrical appliance doesn't work, connect the two electrical appliances in series; If the other appliance is still working without being affected, the two appliances are connected in parallel.

③ Node method: When identifying the circuit, no matter how long the wire is, as long as there is no electrical appliance or power supply in the middle, both ends of the wire can be regarded as the same point, thus finding out the * * * similarity of all electrical appliances.

④ Observation structure method: number the terminals of electrical appliances, with the current inflow end as "head" and the current outflow end as "tail", and observe all electrical appliances. If it is "head → tail → head → tail" in series; If "head, head" and "tail, tail" are connected in parallel.

⑤ Empirical method: For circuits that can't be connected actually, such as street lamps and household circuits, we can judge their connection according to their characteristics.

Fourth, the intensity of current.

1. Current is a physical quantity indicating the strength of current, expressed by I, and the units are Ampere (A), mA and μ A..

1A= 1000mA、 1mA= 1000μA

2. Connection of ammeter

(1) The ammeter must be connected in series with the tested electrical appliance; ② Current flows in from the positive pole of ammeter and out from the negative pole. (3) The measured current shall not exceed the maximum measured value of ammeter.

3, ammeter reading

① The laboratory ammeter has two ranges, 0-0.6a and 0-3a. When measuring, the range of ammeter must be clear. First choose a large range and try to touch it with a switch. If the measured current is 0.6A-3A, it can be measured. If the measured current is less than 0.6a, switch to a smaller range. If the measured current is greater than 3a, switch to an ammeter with a larger range. ② Determine the dividing value of ammeter.

5. Explore the law of current in series-parallel circuit.

The current in the series circuit is equal everywhere: I = i 1 = I2 = i3 = ...

The main loop current in parallel circuit is equal to the sum of each branch current: I = i 1+I2+i3+ ...