What is the knowledge of physics in the second year of high school

1. Quantum theory

Founding mark: In 1900, Planck published the first article "On the Law of Normal Spectral Energy Distribution" in the German "Annals of Physics", marking the birth of quantum theory.

In 1905, the Einstein Prize quantum concept was extended to the propagation of light, and the quantum theory of light was proposed.

In 1913, the British physicist Bohr extended the quantum concept to the energy state inside the atom and proposed a quantized model of atomic structure, which enriched the quantum theory.

2. Thermal radiation phenomenon

Any object emits electromagnetic waves of various wavelengths at any temperature, and the magnitude of its radiant energy and the distribution of radiant energy according to wavelength are related to temperature. This phenomenon of emitting electromagnetic waves due to the thermal excitation of molecules and atoms in matter is called thermal radiation.

Objects both radiate and absorb energy. The greater the coarser the ability of an object to emit electromagnetic waves in a certain frequency range, the greater its ability to absorb electromagnetic waves in that frequency range.

3. Doppler effect

The phenomenon in which the observer perceives a change in frequency due to the relative motion between the wave source and the observer is called the Doppler effect. It was discovered by the Austrian physicist Doppler in 1842.

The frequency of the sound source is equal to the number of complete waves emitted by the source per unit time, and the tone of the sound heard by the observer is determined by the frequency received by the observer, that is, the number of complete waves received per unit time.

4. The law of refraction of light

The refractive index of light when it is injected into a medium from a vacuum is called the absolute refractive index of that medium, which is also referred to as the refractive index of a certain medium.

When light is emitted from one medium to another, although the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant n, for different media, this constant n is different, and this constant n is related to the medium, which is a physical quantity that reflects the optical properties of the medium, and we call it the refractive index of the medium.

5. Total reflection of light

Total reflection phenomenonWhen light enters the optically phobic medium from a light-dense medium, the angle of refraction is greater than the angle of incidence. When the angle of incidence increases to a certain angle, the angle of refraction is equal to 90°, at this time, the refracted light completely disappears, and the incident light is all reflected back into the original medium, this phenomenon is called total reflection.

When the light hits the end surface of the optical fiber bench roll, the light is refracted into the optical fiber, and after many total reflections occur at the interface between the inner core and the coat, it is emitted from the other end of the optical fiber, and does not escape from the jacket, so the light energy loss is very small.

The physics knowledge points of the second year of high school are summarized as follows:

1.Two kinds of charges, the law of conservation of charge, and the meta-charge; The amount of charged body charge is equal to the integer chain multiplier of the element charge.

2.Coulomb's law refers to: f=kq1q2 r2{f:

The force between the point charges (n), k: electrostatic force constant k=, q1, q2: the amount of charge between the two point charges (c), r:

The distance (m) between two charges, the direction is on their line, the force is called and the reaction force is the same charge repels each other, and the different charge attracts each other}.

3.Electric field strength: e=f q (definition, calculation) {e: electric field strength (n c), is the vector (principle of superposition of electric fields), q: the amount of electricity to be tested (c)}.

4.The electric field formed by the charge at the vacuum point (source) e=kq r2{r: the distance from the source charge to the position (m), q: the amount of electricity of the source charge}.

5.The field strength of a uniform electric field e=uab d{uab:ab voltage between two points (v), d:ab distance between two points in the direction of field strength (m)}.

6.Electric field force: f=qe{f: electric field force (n), q: electric charge subjected to electric field force (c), e: electric field strength (n c)}.

The knowledge points of the two compulsory courses of high school physics are summarized as follows:

1. In curvilinear motion, the velocity direction of the particle at a certain time (a certain position) is the tangent direction of this point on the curve.

2. Uniform circular motion: the particle moves in a circular motion, and the arc length is the same in the same time.

3. When the object is moving in a curve, the direction of the external force always points to the concave side of the trajectory.

4. Flat throwing motion: the object is thrown along the horizontal direction of the cover with a certain initial velocity, regardless of air resistance, and the object is only used by gravity to make the movement.

5. Take the throwing point as the coordinate origin, the horizontal direction is the x-axis (the positive direction is the same as the direction of the initial velocity), the vertical direction is the y-axis, and the positive direction is downward.

Summary of physics knowledge points in the second year of high school:

1. Momentum: Momentum can be defined or interpreted from two sides

The product of the mass of an object and its velocity is called the momentum of the object.

Momentum is a measure of the mechanical motion of an object.

The expression for momentum p=mv. Units are: Momentum is a vector quantity, and its direction is the direction of the instantaneous velocity. Because velocity is relative, momentum is also relative.

2. Law of conservation of momentum: When the system is not affected by external forces or the combined external force is zero, the total momentum of the system is conserved. The law of conservation of momentum has a variety of expressions according to the actual situation, and the total momentum before and after the action of the system is usually expressed by the equal sign.

The following issues should be noted when applying the law of conservation of momentum:

The law of conservation of momentum is generally for the system of matter, and it does not make sense to talk about the conservation of momentum for a single object.

For some specific problems, such as collisions, **, etc., in a very short period of time, the interaction force of the objects in the system is much greater than the external force they are subjected to, and these objects can be treated as a system with zero resultant external force, and the law of conservation of momentum is followed in this short period of time.

Velocity is involved in the calculation of momentum, and the velocity of each object in a system of matter must be relative to the same inertial frame of reference, generally using the ground as the reference.

Momentum is a vector quantity, so "total momentum of the system" refers to the vector sum of the momentum of all objects in the system, not the algebraic sum.

The law of conservation of momentum can also be applied to the case of conservation of partial momentum. Sometimes, although the resultant force of the system is not equal to zero, as long as the component of the resultant force on a certain aspect is zero, then the component of the total momentum of the system is conserved in that direction.

The law of conservation of momentum has a wide range of applications. As long as the system is not exposed to an external force or the combined external force is zero, then the law of conservation of momentum applies to the interaction of objects within the system, whether it is gravitational, elastic, frictional, electric or magnetic.