SAT2物理 总结.doc

Wave1. Mechanical waves are periodic disturbances in a medium that transfei energy2.electromagnetic waves donot need a medium for propagation3.waves can be either transverse or longitudinal4.the velocity of a wave is equal to the the product of its frequency and its wavelength5.inference and diffraction are characteristics typical for all waves6.resonance involves matching the natural vibrating vibrating frequency of objects7.nodes are points that do not move in a standing wave8.standing wave node occur every half wavelength .9.diffraction occurs as waves bend around barriers in the same erference can either be constructive (reinforce) or destructive(cancellation)11.superposition is the mixing of waves , which can either add or subtract amplitudes depending on the phases of the interfering waves.Doppler effectLaws of vibrating strings Vibrating air columns (closed pipes open pipes )The number of beats=the difference between the two frequenciesGeometrical optics: Reflection and RefractionNormal 法线 incident light 入射光线 diffuse reflection 漫反射 regular reflection 镜面反射 erect 正立的 center of curvature (C) 两倍焦距 principal focus (F) f=C/21. light is an electromagnetic wave2. The law of reflection states that the angle of incidence is equal to the angle of reflection.3. All angle are measures relative to the normal line.4. Refraction is a change in the direction of light caused by a change in lights velocity as it goes from one transparent medium into another at an oblique angle.5. The absolute index of refractionof a transparent material is equal to the ratio of the velocity of light in air to the velocity of light in the material.6. As light goes form a lower-index material to a high-index material, it slows down and bends toward the normal.7. n1 *sin1=n2*sin28. Total reflection occurswhen the angle of the incidence in the optically denser medium is grater than the critical angle(one condition is must n1:n21)9. Real image can be projected onto a screen. Vitul images cannot be projected and are percieved by the brain as existing on the other side of a mirror.10. Real images can be formed by concave mirror or convex lenses.11. A prism can disperse white light into the colors of the spctrum since the different frequencies of light refract at different angle in the prime.12. Table(1)13. The color of an opaque object is determined by the color of the light it reflects.14. Types of spectra Table(2)15. Convex lens converg; concave lens diverg.16. 1/do+1/di=1/f17. Size of the image/size of object=image distance /object disance=magnification(m)18. Image in palne mirror (1) the image is the same size.(2)the image is erect(3)the image is virtual.Physical opticsInterference and diffractionLight and interference diffraction of light by a gratingThin film interference polarization1. Thomas Young demonstrated light interference in 18012. Interference colors can be seen in thin films and soap bubbles3. The polarization of light is evidence for its transverse nature. Longitudinal waves(such as sound)cannot be polarized.4. POLARIZATION 原理Elements of electronics1. capacitors store charge in simple circuits.2. Heated metals can emit electrons.3. In a vacuum tube, a hot filament emits a beam of electrons that can be controlled by electromagnetic field and potential differences.4. Q=CV C (farad)5. Potential energy =6. In series7. In parallel8. Thermionic emission:heated metal the part that is heated so that it will give off electrons is called the cathode.Electricity1. electric charge are positive or negative2. Coulombs law is described as an inverse square law for static charges.3. Electric field lines show the direction that a positive test charge would travel.(?)4. The electrical potential difference (voltage)is a measure of the work done per unit charge5. Conventional current indicates the flow of positive charge una circuit.6. Ohms law related the voltage in a circuit to the current and electrical resistance.7. Seried circuit have the same current throught,but the potential drops are shared proportionally among the various resistors.8. Parallel circuits have the same potential diffence across each resistor,but the current is divided along the circuits inversely proportional to amount of resistabce in a branch.9. Kirchhoffs rule says that the sum of the currents entering a branch must equal to the sum of the currents leaving a branch in a parallel circuit.10. Joules law Q= 11. Power P=VI12. The combined resistors in parallel is always less than the smallest resistance.13. The internal resistance can be treated as anexternal resistance VT=emf-Ir14. Resistance(ohm) R=kL/A metallic is increase when temperature rises 15. Conductivity is the reciprocal of resistivity Magnetism10. the field lines around terrestrial magnets flow from north to south as indicated by a magnetic compass11. An electric current can generate a magnetic field12. The direction of electromagnetic field can be determined using right-hand rules13. Interacting electromagnetic fields can produce forces in current-carrying wires or on moving electric charges14. An electric meter (voltmeter or ammeter)can be develped based on the twisting force on a wire caused by interacting electromagnetic field.15. A wire moving in a magnetic field can have a current induced in it.16. The magnetic flux of a current induced in a wire always opposes the magnetic flux of the current that induces it. The Lenzs law.17. secondary emf/primary emf=number of turns on secondary/number of turns on primary18. VsIs=VsIs*efficiencyQuantum theory and nuclear phsics Photoelectric effect nuclear changes atomic models subatomic particles and accelerators fission and fusion radioactivity1. photoelectric effect:(1)the light consist of photos (2)cannot be explained by the wave theory of light2. The maximum kinetic enery of emitted electrons is independent of the intensity of the incident light but varies directly with the frequency of the incident light.3. Planks constant (h) is a universal constant that governs the quantum models of light and atoms.4. Bohr