| Back to logs list
2080284 2010 年 11 月 05 日 19:45 Reading (loading. ..) Comments (0) Category: Personal Diary
The first chapter Stop the sound vibrations have stopped. Vibrating object call source.
2, voice transmission requires medium vacuum can not transfer sound.
3, the sound propagation velocity in the medium referred to the speed of sound. Sound in air at 15 ℃, the propagation velocity is 340m / s.
4,
今天你偷菜了吗？, the echo is due to the propagation of sound is reflected back to encounter obstacles formed.
Second, how do we hear the sound
1, the sound in the ears of transmission: the outside world heard the voice of the tympanic membrane caused by vibration, the vibration by the ossicles and other organizations to pass the auditory nerve, auditory nerve to signal to the brain, people heard the sound.
2, deafness: is divided into nerve deafness and conduction deafness.
3, bone conduction: the transmission of sound can be used not only the ears, but also by skull, jaws spread to the auditory nerve, causing hearing. This is called bone conduction of sound conduction. Some loss of hearing people can hear the sound this way.
4, binaural effect: People have two ears, rather than one. Sound source to the general different from the two ears, the sound reached the ears of the time, strength and other characteristics is different. These differences are important to determine the basis of sound source direction. This is the binaural effect.
Three music and three features
1, music is the object doing the sound vibration of the rules.
2, pitch: high and low voices of people feel. Audible tone the body with the vibration frequency are related, the higher the frequency the higher the pitch; frequency the lower the bass tone. 1s the number of objects called the frequency of vibration, the higher the frequency the faster the object vibration.
3, loudness: the voice of people feel the size of the ear. Loudness and the amplitude of the body with the occurrence of distances from the sound on. Object vibration, the maximum distance from the original position is called amplitude. The greater the amplitude the greater the loudness.
4, sound: the decision by the object itself. People under the instrument or voice to identify the distinction between people.
IV, noise hazards and control
1, the four contemporary society pollution: noise pollution, water pollution, air pollution, solid waste pollution.
2, physics point of view, noise is the sound rules of the body do not sound chaotic vibration; environmental noise is the point of view impedes the normal rest, study and work, sound, and to listen to people interference from the sound of the voice.
3, people in decibels (dB) divided by the sound level.
4, reduced noise, the method: in the sound source at the weakened, weakened in the dissemination process, in the human ear at the weakening.
V.
can use sound to the dissemination of information and transmission of sound energy
Chapter: Definition: the ability to name objects emitting light.
2, rule: a homogeneous medium in the same light is spread along a straight line.
3, light a small beam of light from the abstract ideal physical model established, the establishment of an ideal physical model is to study the physics of the commonly used methods.
4, applications and phenomena:
① laser alignment.
② shadow formation.
③ eclipses formation.
④ pinhole imaging.
5, the speed of light: C = 3 × 108m / s = 3 × 105km / s.
Second, the light reflection
1, definition: a medium of light fired from the surface of another medium, part of the light is reflected back to the original media, the phenomenon is called the reflection of light.
2, law of reflection: reflected light and incident light, normal in the same plane, the reflected light and incident light separated the sides in the normal, the angle of reflection equals angle of incidence. A coherent state of light reflection road is reversible.
3, Category:
⑴ mirror reflection:
Definition: parallel light hitting the object plane is still parallel after reflection
conditions: smooth reflective surface.
⑵ diffuse reflection:
Definition: hitting the material surface after reflection of parallel light toward different directions, each light to comply with the law of reflection of light.
conditions: reflective surface uneven.
4, mirror :
⑴ plane mirror: Imaging Features: ① like, things like equal
②, physical distance is equal to the mirror.
③ like, physical connection with the mirror plane perpendicular to
④ object like a mirror in the virtual image into.
imaging principle: light reflection theorems
real image and virtual image: the real image: the actual convergence point of light into the image
virtual image: the light reflected back by the extension cord into the converging point of the image
III color and invisible light
1, the composition of white light: red, orange, yellow, green, blue, indigo, violet.
2, can not see the light: infrared, ultraviolet
Chapter phenomenon.
2, light refraction law:
⑴ refraction of light, light rays, and normal in the same plane.
⑵ refracted light and incident light separation and normal sides.
⑶ light slanting into the water from the air or other medium, the angle of refraction is less than the angle of incidence is nearly normal refraction.
light dipped from the water or other media into the air, the angle of refraction greater than the angle of incidence, are far from normal refraction.
vertical injection light from the air (or other media injection), angle of refraction = angle = 0 degrees.
Second, the lens
1, noun: thin lens: the lens is much smaller than the thickness of the sphere radius.
main axis: a straight line through the two spherical center of the sphere.
optical center: (O) is the center of a thin lens. Nature: the light through the optical center does not change the direction of propagation.
focus (F): with the main axis parallel to the lens makes the light converge at a point on the main axis, this point called the focus.
focal length (f): the focus of the distance to the lens optical center.
three
convex imaging lens imaging law rules table:
object distance image distance as the nature of the application
down, is placed, shrinking virtual, real
u> 2f narrow inverted real image f 2f slide
u u magnifying glass
four, eyes and glasses, myopia and
correction of hyperopia: myopia to wear concave, convex lens to wear hyperopia.
five, microscopes and telescopes
IV, the extent that the object of hot and cold temperatures.
2, Unit:
① international system of units used in the thermodynamic temperature.
② common units are degrees Celsius (℃) provides that: the standard atmospheric pressure in a mixture of ice water temperature of 0 degrees, the temperature of boiling water is 100 degrees, divided into 100 equal parts between them, each of equal parts of a 1 degree Celsius is called temperature of -3 ℃ to read as: minus 3 degrees Celsius, or minus 3 degrees Celsius
③ conversion between T = t + 273K
3, measure - the thermometer (usually liquid thermometer)
thermometer principle: the use of liquid work expansion and contraction.
classification and comparison:
classification experiment with a thermometer thermometer thermometer measured body temperature measuring purposes
measured at room temperature
range -20 ℃ ~ 110 ℃ -30 ℃ ~ 50 ℃ 35 ℃ ~ 42 ℃
dividing the value of 1 ℃ 1 ℃ 0.1 ℃
kerosene used in liquid mercury (red) and alcohol (red) special structure of the glass bulb mercury
top of necking
can not use the rejection method uses the measured objects can not be thrown away objects can be read to leave the body before use common thermometer readings
use:
before use: observation of its range, to determine the suitability of the temperature of the object under test; and recognize the thermometer scale value for accurate readings. Used: glass bulb thermometer immersed in all the tested liquid, do not touch the container or container end wall; thermometer bulb immersed in the liquid under test wait a while until the thermometer shows the number of stability after the reading; reading of the glass bulb to remain in the fluid to be measured, the line of sight with the thermometer in the liquid column of the upper surface of the phase level.
Second, the physical state change of state
fill the name and endothermic heat conditions:
1, melting and solidification of molten
①:
definition: an object is called from a solid into a liquid melting.
crystal material: Hyperion, ice, quartz crystal, amorphous material: resin, glass, paraffin, asphalt, beeswax
salt, alum, Chennai, molten metal
Image :
② solidification:
definition: material from liquid to solid is called freezing.
solidification Image:
2, gasification and liquefaction:
① vaporization:
definition: material from liquid to gas is called vaporization.
Definition: liquid at any temperature can occur, and only the vaporization of the liquid surface of the phenomenon is called evaporation .
factors: ⑴ the temperature of the liquid; ⑵ ⑶ liquid surface of liquid surface area of air flow.
effects: evaporation endothermic (absorbing heat from the outside world or their own), with the cooling.
Definition: at a certain temperature, the liquid surface of simultaneous internal and intense vaporization phenomenon.
Boiling point: the temperature of boiling liquid.
boiling conditions: ⑴ the boiling point. ⑵ endothermic
boiling point and pressure to the relationship: all of the liquid's boiling point is lower air pressure decreases, pressure increases, increased
② liquefaction: Definition: material from the gas into liquid is called liquefaction.
Methods: ⑴ lower the temperature; ⑵ compression volume.
3, sublimation and sublimation:
① sublimation definition: material from a solid directly into the process gas, heat, easy to sublimate the material are: iodine , ice, dry ice, camphor, tungsten.
② Ning Hua Dingyi: material from the process gas directly into a solid, heat
chapter a current
2, the provisions of direction: the direction of movement of positive charge the direction of the current provisions.
3, the conditions for sustained current:
circuit in the power circuit to access
4, the current three effects.
(1), heating effect of current. (2), current magnetic effects. (3), current chemistry.
5, unit: (1), the International Unit: A (2),
如果我们分手了，我怎么办，你怎么办。, commonly used units: mA, μA
(3) , conversion relationship: 1A = 1000mA 1mA = 1000μA
6, measuring: First, the electric power:
1, define: current work done by a certain circuit called the electric power.
2, in real terms: the current process of doing work, the actual energy is converted into other forms of energy (power consumption) process.
3, states: current work done by a certain circuit, this circuit is equal to the voltage across the current in the circuit and the power-time product.
4, the formula: W = UIt = Pt (applicable to all circuits)
For pure resistance circuit can be derived from: W = I2Rt = U2t / R
5 , unit: International unit is the joule (J) common unit: degree (kwh) 1 ° = 1 kWh = 1 kwh = 3.6 × 106J
6, measurement of electric power:
⑴ Meter: measuring the user to use electrical appliances made in the power of a period of time power (power consumption of a certain period of time) of the instrument.
⑵ power meter on the
⑶ reading: meter readings before and after the difference between the two is the degree of electricity during this period.
Second, the electric power:
1, Definition: current work done per unit time.
2, the physical meaning: that the current pace of physical work done depends on the brightness of the lamp bulb the size of the actual power.
3, electric power formula: P = UI = W / t (for all circuits)
For pure resistance circuit can be derived: P = I2R = U2 / R
4, Unit: IU Watt (W) common units: kilowatt (kw)
5, rated power and actual power:
⑴ Rated voltage: when working with electrical voltage.
Rated Power: The electrical power at rated voltage. P = U Amount Amount Amount = U2 amount of I / R
⑵
P = W / t can be used two sets of units: UI ② Circuit:
three electric
1, Experiment: Objective: To study the heat current through a conductor with those factors.
2, Joule's law: the heat generated by current through a conductor with the current proportional to the square is proportional with the resistance of the conductor, with the power proportional to the time.
3, the formula: Q = I2Rt (applicable to all circuits) for the pure resistance circuit can be derived: Q = UIt = U2t / R = W = Pt
4, Application - electric heater
four power consumption
(a), the family circuit:
1, the family circuit components: low-voltage power lines (FireWire zero line), power meter, knife switch, fuse, electrical appliances, sockets, lamp holders, switch.
2, the family connection to the circuit: in parallel with electrical access to a variety of circuits, receptacles and lampholders are connected in parallel to control the use of electrical switches and electrical work is in series.
3, the various parts of the circuit family:
⑴ low-voltage power lines:
⑵ Meter:
⑶ Knife (air switch):
⑷ fuse box:
⑸ outlet:
⑹ appliances (light), switch:
(b), family reasons for overcurrent circuit:
reasons: a short circuit, the total electrical power used is too large.
(c), safe use of electricity:
safe use of electricity: do not touch the body do not live near high-voltage low-voltage electrified body
Chapter VI, (a), the role of voltage
1, the formation of current in voltage: the voltage to the circuit directional movement in the formation of free charge current. Power is to provide a voltage device.
2, the circuit conditions for sustained current ① circuit in power supply (or circuit voltage at both ends) ② circuit is connected.
(b), the voltage of the unit
1, international units: V common unit: kV mV, μV
conversion relationship: 1Kv = 1000V 1V = 1000 mV 1 mV = 1000μV
2, remember Some voltage values: a battery 1.5V a battery voltage of 220V 2V family safe voltage is not higher than 36V
(c), voltage measurement :
1, instrument: voltage meter, symbol:
2, reading When the subject of the terminal to see the range, one big grid, each small grid voltage
3, using the rules: ① voltage meter to be parallel in the circuit.
② current from the voltage meter Otherwise, the pointer will reverse bias.
③ voltmeter measured the voltage should not exceed the maximum range.
Second, resistance
(a ) of the definition and symbols:
1, definition: resistance that hinder the role of conductor on the current size.
2, symbol: R.
(b) Unit:
1, international units : ohms. Provides that: If the voltage across the conductor is 1V, the current through the conductor is 1A, this conductor resistance is 1Ω.
2, commonly used units: thousands of Europe, megohm.
3, conversion : 1MΩ = 1000KΩ 1 KΩ = 1000Ω
4, to understand some resistance: a small flashlight bulb, the filament resistance of a few dozen in Europe to Europe. Daily use of the incandescent filament resistance of a few hundred to several thousand Euro in Europe. Laboratory of copper wire, resistance is less than a few percent of Europe. Zero resistance ammeter as a few ohms. The internal resistance of voltage meter is about for thousands of Europe.
(c) factors:
Conclusion: resistance of the conductor is a conductor's own nature, its size depends on the conductor material, length and cross sectional area, but also with the temperature.
(d) classification
1, set the value of resistance: Circuit symbol:.
2, variable resistor (rheostat): circuit symbols.
⑴ sliding rheostat:
Construction: ceramic tube, coil, slide film, metal rods, terminal
structure diagram:
.
variable resistance principle: access to the circuit by changing the length of the resistance line to change the resistance.
functions: ① the resistance of the circuit by changing gradually change the current in the circuit and the voltage across some circuit protection circuit
⑵ ② resistance box.
Third, Ohm's law.
1, to explore current and voltage, resistance relationship.
Conclusion: The resistance of certain circumstances, the conductor of the current and the increase is proportional to the voltage across the conductor; in the case of constant voltage, the current conductor is inversely proportional to the resistance of the conductor.
2, the content of Ohm's law: the current conductor, with the voltage across the conductor is proportional to the resistance is inversely proportional with the conductor.
3, mathematical expressions I = U / R
IV TESTING RESISTANCE
1, definition: a voltmeter and ammeter circuits were measured voltage across a conductor and through the current Ohm's law can be calculated according to the resistance of the conductor, this resistor with a voltage meter ammeter method is called voltammetry.
2, the principle: I = U / R
3, the schematic : (right)
five series circuit features:
1, current: Text: series circuit currents are equal around.
letter: I = I1 = I2 = I3 = ... ... In
2, Voltage: Text: series circuit the total voltage is equal to the sum of all parts of the circuit voltage.
letter: U = U1 + U2 + U3 + ... ... Un
3, Resistance: Text: The total resistance of series circuit is equal to the sum of all parts of the circuit resistance.
letters: R = R1 + R2 + R3 + ... ... Rn
six parallel circuit characteristics :
1, current: Text: parallel circuit the total current is equal to the sum of current in each branch.
letter: I = I1 + I2 + I3 + ... ... In
2 , Voltage: Text: parallel circuit the voltage across each branch are equal.
letter: U = U1 = U2 = U3 = ... ... Un
3, Resistance: Text: parallel circuit is equal to the reciprocal of total resistance of each branch resistance reciprocals.
letters: 1 / R = 1/R1 +1 / R2 +1 / R3 + ... ... 1/Rn
Chapter VIII of the, Magnetic: Magnets attract iron, cobalt, nickel and other material properties (absorption of iron)
2, magnet: Definition: a magnetic material
Category: permanent magnet is divided into natural and artificial magnets
3, the magnetic pole : Definition: the strongest part of the magnet is called magnetic poles. (The weakest among the strongest magnets at both ends)
Type: free rotation of the magnet level, the guide is called the Antarctic pole (S), refers to the north magnetic pole is called the Arctic (N)
role of law: the same name as mutually exclusive poles,
孙悟空为什么总是搞不定沿途的妖怪？, Synonyms poles attract each other.
4, magnetization: ① Definition: to make objects that have not received magnetic magnetic process.
② magnetized steel and soft iron: soft iron is magnetized, the magnetic easy to disappear, known as soft magnetic materials. Steel is magnetized, the magnetic properties of long-term, referred to as hard magnetic materials.
Second, the magnetic field:
1, definition: the existence of the material surrounding the magnet, it is an invisible, intangible special material.
2, basic properties: the magnetic field into which the magnets have on the force. The interaction between magnetic poles by magnetic field occur.
3, the direction of states: a point in a magnetic field, a small needle under the direction of the North Pole rest (small needle in the direction of magnetic North Pole suffered) is the point of the magnetic field direction.
4, magnetic flux lines:
① Definition: some paintings in the magnetic field direction of the curve. Direction of the curve at any point on the point of needle related to the North Pole under the same direction.
② direction: a sense of magnet wire around the magnetic North Pole is from the magnets out, back to the South Pole magnets.
5, magnetic force: a point in a magnetic field, the direction of magnetic North Pole suffered with the magnetic field at that point the same direction, the direction of the Antarctic suffered with the magnetic field points in opposite directions.
6, Category:
Ι, the geomagnetic field:
① Definition: there is space around the Earth's magnetic field, the needle guide to the North was due to magnetic field.
② poles: the North Pole to the magnetic field near the geographic South Pole, the geomagnetic field near the South Pole in the geographic North Pole.
③ magnetic declination: the first discovery by the Shen Kuo of the Song Dynasty.
Ⅱ, current magnetic field:
① Oersted experiment: there is the magnetic field around the power wires, known as the current magnetic effects. The phenomenon in 1820 Danish physicist Oersted was found. This phenomenon indicates that: there is the magnetic field around the power wires, and on the direction of the magnetic field and current.
② the magnetic field of Galvanized: Galvanized bar magnet magnetic field and magnetic field of the same. Polarity at both ends with the current direction is related to the current direction of the relationship between magnetic poles is set to judge by the amp.
③ Application: Solenoid
three electromagnetic induction:
1, History: British physicist Michael Faraday discovered.
2, the induced current:
induced current in the direction of the conductor with the direction of motion and magnetic field related.
4, Application - alternator
5, AC and DC:
Fourth, the role of magnetic fields on the current:
1, energized conductor in a magnetic field in the direction of the force, with the current direction and For the magnetic field direction.
2, Applications - DC motor
Chapter molecular composition of the
3, solid, liquid and gaseous micro-model:
4, atomic structure
5, nano science and technology
Second, the quality:
1, Definition: substances contained objects the number of call quality.
2, Unit: International System of Units: Main unit kg, commonly used units: tg mg
3, the quality of understanding: the quality of solid form with the objects, status, location, temperature change, so the quality is the object itself of a property.
4, measurement:
Second, density:
1, definition: a substance per unit volume is called the quality of the density of the substance.
2, formula: deformation
3, Unit: International System of Units: Main unit kg/m3, common units of g/cm3. Comparison of two units: g/cm3 units large. Unit conversion relationship: 1g/cm3 = 103kg/m3 1kg/m3 = 10-3g / cm3 the density of water 1.0 × 103kg/m3, read as 1.0 × 103 kg per cubic meter, which indicates the physical meaning is: 1 cubic meter Water quality is 1.0 × 103 kg.
4, measuring the volume - measuring cylinder (cup)
5, measuring the density of the solid
Chapter XI, material
1, define: To study the motion of an object assuming the object is called the fixed point of reference.
2, can be any object reference
3, choose a different object reference to observe the same conclusion may be different. The same motion or stationary object is dependent on the selected frame of reference, this is the relativity of movement and stillness.
Second, the mechanical movement
1, Definition: Physical changes in the location of the object is called the mechanical motion.
2, features: mechanical movement is the most common phenomenon in the universe.
3, comparing the speed of object motion method:
⑴ the same time, the movement away from long-distance fast
⑵ the same time, the movement quickly
⑶ short comparison unit time away.
Category: (based on movement routes) ⑴ curved linear motion
Ⅰ ⑵ uniform linear motion:
A, Definition: same speed along the straight line motion is called uniform motion.
Definition: uniform motion, speed equal to the moving object in the distance per unit time.
physical meaning: the movement of objects as fast as the speed of the physical quantities that
formula:
B, speed : International System of Units m / s transport unit km / h in the two units of m / s units big.
Conversion: 1m / s = 3.6km / h.
Ⅱ variable motion:
definition: the movement velocity of change is called variable motion.
average speed: total time = total distance
physical meaning: that the average speed of variable speed motion
five, force the effect
1, the concept of force: force is the role of objects on the object.
2 the nature of power: the role of forces between objects to each other (in any case the interaction force is equal and opposite effects on different objects.) Interaction between two objects when the object is also the force of a body, and vice versa, is also the force of a body object.
3, effect of force: force can change an object's motion state. Force can change the shape of the object.
4, a unit of force: The International System of Units in a unit of force is the Newton referred to as cows, with N said.
perceptual force: two eggs about the force used by 1N.
5, force measurement:
⑴ dynamometer: a tool for measuring the size of the force.
⑶ spring dynamometer:
6, the three elements of power: force size, direction, and function points.
7, force representation
six, inertia, and inertia:
1, Newton's First Law:
⑴ content of Newton's first law: all the objects in the absence of a force of the effects of The total remain at rest or of uniform linear motion state.
2, inertia:
⑴ definition: the object properties remain constant state of motion is called inertia.
⑵ Description: Inertia is a property of objects. In any case, all objects have inertia.
seven, two force balance:
1, definition: objects in the role by the two forces, if they can remain at rest or of uniform linear motion, said second state of equilibrium .
2, two equilibrium conditions: two forces acting on the same object, the size of the equal and opposite, the two forces in a straight line
3, the relationship between force and motion states:
force conditions of the object Motion of the state that force is not generated
(maintain) the reasons for movement
together by non-equilibrium force
0
force is not the object is to change the state of motion because
Chapter XII,
2, plastic: deformation occurs in the force, loss of power can not restore the original shape of the nature of the call plasticity.
3, elastic: the elastic deformation of the object by the force is called elastic, elastic deformation of the size of the size and flexibility
Second, gravity:
⑴ the concept of gravity: objects near the ground, as the Earth by the force of attraction which is called gravity. Force of gravity an object is: Earth.
⑵ formula for calculating the size of gravity G = mg where g = 9.8N/kg It said the quality suffered 1kg object gravity 9.8 N.
⑶ gravity direction: straight down the application is re-vertical, a level, if the wall were examined whether the level of vertical and surface.
⑷ point of gravity - the center of gravity:
three friction:
1, definition: two objects in contact with each other, when they want to or have occurred relative movement will be in contact with surface hinder the relative motion to generate a force called friction.
2, Category
Marc Jacobs Handbags Know More About High Heel Sho
Hybrid Mode
