1. Movement of particle (1) ------Linear motion

1) Uniform speed linear motion

1. Average speed V = s/t (definition formula) 2. Useful inference Vt2-Vo2=2as

3. Intermediate speed Vt/2=V flat=(Vt+Vo)/2 4. Final speed Vt=Vo+ at

5. Intermediate position speed Vs/2=[(Vo2+Vt2)/2]1/2 6. Displacement s=V flat t=Vot+at2/2=Vt/2t

7. Acceleration a=(Vt-Vo)/t {With Vo as the positive direction, a and Vo are in the same direction (acceleration) a>0; in the opposite direction, a<0}

8 .Experimental inference Δs=aT2 {Δs is the difference between displacements in consecutive equal times (T)}

9. Main physical quantities and units: initial velocity (Vo): m/s; acceleration (a ): m/s2; terminal speed (Vt): m/s; time (t) seconds (s); displacement (s): meters (m); distance: meters; speed unit conversion: 1m/s=3.6km/ h.

Note:

(1) The average speed is a vector;

(2) The object’s speed is large, but the acceleration is not necessarily large;

(3) a=(Vt-Vo)/t is only a measurement formula, not a determinant;

(4) Other related content: particle, displacement and distance, reference system, time and moment [see first Volume P19]/s--t diagram, v--t diagram/speed and velocity, instantaneous speed [see Volume 1 P24].

2) Free fall motion

1. Initial velocity Vo=0 2. Final velocity Vt=gt

3. Drop height h=gt2/2 ( Calculate downward from the Vo position) 4. Infer Vt2 = 2gh

Note:

(1) Free falling motion is a uniformly accelerated linear motion with an initial velocity of zero, following a uniformly variable speed straight line Law of motion;

(2)a=g=9.8m/s2≈10m/s2 (gravitational acceleration is smaller near the equator, smaller in the mountains than on the flat ground, and the direction is vertically downward).

(3) Vertical upward throwing motion

1. Displacement s=Vot-gt2/2 2. Final speed Vt=Vo-gt (g=9.8m/s2≈10m /s2)

3. Useful inference Vt2-Vo2＝-2gs 4. Maximum rising height Hm＝Vo2/2g (from the throwing point)

5. Round trip time t＝ 2Vo/g (time from thrown back to original position)

Note:

(1) Whole process processing: It is a uniform deceleration linear motion, with upward as the positive direction, acceleration Take a negative value;

(2) Segmented processing: upward is uniform deceleration linear motion, downward is free fall motion, symmetrical;

(3) Ascent and fall process It has symmetry, such as equal and opposite speeds at the same point.

2. Movement of the particle (2)----curvilinear motion, universal gravitation

1) Horizontal throwing motion

1. Horizontal speed: Vx＝ Vo 2. Vertical speed: Vy=gt

3. Horizontal displacement: x=Vot 4. Vertical displacement: y=gt2/2

5. Movement time t＝(2y/g)1/2 (usually expressed as (2h/g)1/2)

6. Resultant speed Vt＝(Vx2+Vy2)1/2＝[Vo2+(gt )2]1/2

The angle β between the direction of the resultant velocity and the horizontal: tgβ＝Vy/Vx＝gt/V0

7. The resultant displacement: s＝(x2+y2) 1/2,

The angle α between the displacement direction and the horizontal direction: tgα＝y/x＝gt/2Vo

8. Horizontal acceleration: ax=0; vertical acceleration: ay＝g

Note:

(1) The horizontal throwing motion is a uniform curved motion with an acceleration of g. It can usually be regarded as a uniform linear motion in the horizontal direction and a vertical motion. The synthesis of free fall motion;

(2) The movement time is determined by the falling height h(y) and has nothing to do with the horizontal throwing speed;

(3) The relationship between θ and β is tgβ=2tgα;

(4) In the flat throwing motion, time t is the key to solving the problem; (5) Objects moving in a curve must have acceleration. When the direction of the speed is not in the direction of the resultant force (acceleration) When on the same straight line, the object moves in a curve.

2) Uniform circular motion

1. Linear velocity V＝s/t＝2πr/T 2. Angular velocity ω＝Φ/t＝2π/T＝2πf

3. Centripetal acceleration a＝V2/r＝ω2r＝(2π/T)2r 4. Centripetal force Fcenter＝mV2/r＝mω2r＝mr(2π/T)2＝mωv=F合

5. Period and frequency: T=1/f 6. The relationship between angular velocity and linear velocity: V=ωr

7. The relationship between angular velocity and rotational speed ω=2πn (the meaning of frequency and rotational speed here Same)

8. Main physical quantities and units: arc length (s): meter (m); angle (Φ): radian (rad); frequency (f): hertz (Hz); period (T ): second (s); rotation speed (n): r/s; radius?: meter (m); linear velocity (V): m/s; angular velocity (ω): rad/s; centripetal acceleration: m/s2 .

Note:

(1) The centripetal force can be provided by a specific force, the resultant force, or the component force. The direction is always perpendicular to the speed direction and points to the center of the circle. ;

(2) For an object in uniform circular motion, its centripetal force is equal to the resultant force, and the centripetal force only changes the direction of the speed, not the magnitude of the speed. Therefore, the kinetic energy of the object remains unchanged, and the centripetal force does not do work, but Momentum keeps changing.

3) Universal gravitation

1. Kepler’s third law: T2/R3=K (=4π2/GM) {R: orbital radius, T: period, K: constant (It has nothing to do with the mass of the planet, it depends on the mass of the central celestial body)}

2. The law of universal gravitation: F=Gm1m2/r2 (G=6.67×10-11N?m2/kg2, the direction is on the line connecting them (Up)

3. Gravity and gravitational acceleration on celestial bodies: GMm/R2=mg; g=GM/R2 {R: celestial body radius (m), M: celestial body mass (kg)}

4. Satellite orbiting speed, angular velocity and period: V＝(GM/r)1/2; ω＝(GM/r3)1/2; T＝2π(r3/GM)1/2{M : Mass of central celestial body}

5. The first (second and third) cosmic velocity V1 = (g ground r ground) 1/2 = (GM/r ground) 1/2 = 7.9km/s; V2＝11.2km/s; V3＝16.7km/s

6. Geostationary satellite GMm/(rground+h)2＝m4π2(rground+h)/T2{h≈36000km, h : Height from the earth's surface, r: Radius of the earth}

Note:

(1) The centripetal force required for the movement of celestial bodies is provided by universal gravity, F = F million; < /p>

(2) The mass density of celestial bodies can be estimated by applying the law of universal gravitation;

(3) Geostationary satellites can only operate above the equator, and their operation period is the same as the earth’s rotation period;

(3) p>

(4) As the satellite orbit radius becomes smaller, the potential energy becomes smaller, the kinetic energy becomes larger, the speed becomes larger, and the period becomes smaller (three opposites at the same time);

(5) The maximum orbit of the earth satellite The speed and minimum launch speed are both 7.9km/s.

3. Force (common forces, synthesis and decomposition of forces)

1) Common forces

1. Gravity G = mg (direction vertical Downward, g=9.8m/s2≈10m/s2, the point of action is at the center of gravity, applicable to the vicinity of the earth's surface)

2. Hooke's law F=kx {direction along the direction of recovery deformation, k: force Degree coefficient (N/m), x: deformation amount (m)}

3. Sliding friction force F = μFN {opposite to the relative movement direction of the object, μ: friction factor, FN: positive pressure (N )｝

4. Static friction force 0 ≤ f static ≤ fm (opposite to the relative motion trend of the object, fm is the maximum static friction force)

5. Universal gravitational force F = Gm1m2/r2 ( G=6.67×10-11N?m2/kg2, the direction is on their connection line)

6. Electrostatic force F=kQ1Q2/r2 (k=9.0×109N?m2/C2, the direction is on their connection line) on the connection)

7. Electric field force F = Eq (E: field strength N/C, q: electric charge C, the electric field force on the positive charge is in the same direction as the field strength)

< p>8. Ampere force F=BILsinθ (θ is the angle between B and L, when L⊥B: F=BIL, when B//L: F=0)

9. Loren The force f=qVBsinθ (θ is the angle between B and V, when V⊥B: f=qVB, when V//B: f=0)

Note:

(1) The stiffness coefficient k is determined by the spring itself;

(2) The friction factor μ has nothing to do with the pressure and contact area, and is determined by the material properties and surface conditions of the contact surface;

(3) fm is slightly larger than μFN, generally regarded as fm≈μFN;

(4) Other related content: static friction (magnitude, direction) [see Volume 1 P8];

(5) Physical quantity symbols and units B: magnetic induction intensity (T), L: effective length (m), I: current intensity (A), V: charged particle speed (m/s), q: charged Particle (charged body) charge (C);

(6) The directions of Ampere force and Lorentz force are determined by the left-hand rule.

2) The synthesis and decomposition of forces

1. The synthesis of forces on the same straight line is in the same direction: F＝F1+F2, and in the opposite direction: F＝F1-F2 (F1>F2 )

2. The synthesis of mutual angular forces:

F＝(F12+F22+2F1F2cosα)1/2 (cosine theorem) When F1⊥F2: F＝(F12+ F22)1/2

3. Resultant force size range: |F1-F2|≤F≤|F1+F2|

4. Orthogonal decomposition of force: Fx=Fcosβ, Fy=Fsinβ (β is the angle between the resultant force and the x-axis tgβ=Fy/Fx)

Note:

(1) The synthesis and decomposition of force (vector) follow parallelism Quadrilateral rule;

(2) The relationship between the resultant force and the component forces is an equivalent substitution relationship. The resultant force can be used to replace the identical action of the component forces, and vice versa;

( 3) In addition to the formula method, the graph method can also be used to solve the problem. At this time, the scale must be selected and the graph must be drawn strictly;

(4) When the values ??of F1 and F2 are constant, the angle between F1 and F2 The larger the (α angle), the smaller the resultant force;

(5) The resultant force on the same straight line can be taken in the positive direction along the straight line, and the positive and negative signs are used to indicate the direction of the force, which is simplified to algebraic operations.

4. Dynamics (motion and force)

1. Newton’s first law of motion (law of inertia): Objects have inertia and always maintain a state of uniform linear motion or rest until Until an external force forces it to change this state

2. Newton's second law of motion: F combined = ma or a = F combined / ma {determined by the combined external force, consistent with the direction of the combined external force}

3. Newton’s third law of motion: F=-F? {The negative sign indicates opposite directions, F and F? each act on the other, the difference between balance force and action force reaction force, practical application: recoil motion} < /p>

4. ***The balance F of point forces = 0, generalize {orthogonal decomposition method, three force convergence principle}

5. Overweight: FN>G, weight loss: G Dealing with high-speed problems is not applicable to microscopic particles [see Volume 1 P67]

Note: The equilibrium state means that the object is at rest or in a straight line at a constant speed, or is rotating at a constant speed.

5. Vibration and waves (mechanical vibration and propagation of mechanical vibration)

1. Simple harmonic vibration F = -kx {F: restoring force, k: proportional coefficient, x: Displacement, the negative sign indicates that the direction of F is always opposite to x}

2. Simple pendulum period T=2π(l/g)1/2 {l: pendulum length (m), g: local gravity Acceleration value, conditions for establishment: swing angle θ<100;l>>r}

3. Forced vibration frequency characteristics: f=f driving force

4. *** occurs Vibration conditions: f driving force = f solid, A = max, prevention and application of vibration [see Volume 1 P175]

5. Mechanical waves, transverse waves, longitudinal waves [see Volume 2 P2]

6. Wave speed v=s/t=λf=λ/T{During wave propagation, one wavelength propagates forward in one cycle; the wave speed is determined by the medium itself}

7. The wave speed of sound waves (in air) 0℃: 332m/s; 20℃: 344m/s; 30℃: 349m/s; (sound waves are longitudinal waves)

8. The waves undergo obvious diffraction ( The wave continues to propagate around the obstacle or hole) Condition: The size of the obstacle or hole is smaller than the wavelength, or the difference is not large

9. Wave interference conditions: the two waves have the same frequency (constant phase difference, constant amplitude Close to each other, the vibration direction is the same)

10. Doppler effect: Due to the mutual movement between the wave source and the observer, the wave source transmitting frequency and the receiving frequency are different. {As they approach each other, the receiving frequency increases, and conversely, the receiving frequency decreases. Small [see Volume 2 P21]}

Note:

(1) The natural frequency of an object has nothing to do with the amplitude and driving force frequency, but depends on the vibration system itself;

(2) The strengthening area is where the wave crest meets the wave crest or the wave trough meets the wave trough, and the weakening area is where the wave crest meets the wave trough;

(3) The wave only propagates vibration, and the medium itself does not occur along with the wave. Migration is a way of transferring energy;

(4) Interference and diffraction are unique to waves;

(5) Vibration images and wave images;

(6) Other related content: Ultrasonic waves and their applications [see Volume 2 P22]/Energy conversion in vibration [See Volume 1 P173].

6. Impulse and momentum (changes in force and momentum of an object)

1. Momentum: p=mv {p: momentum (kg/s), m: mass ( kg), v: speed (m/s), the direction is the same as the speed direction}

3. Impulse: I＝Ft {I: impulse (N?s), F: constant force (N), t: The action time of force (s), the direction is determined by F}

4. Momentum theorem: I=Δp or Ft=mvt–mvo {Δp: momentum change Δp=mvt–mvo, which is a vector formula }

5. Law of conservation of momentum: total before p = total after p or p = p'? It can also be m1v1+m2v2=m1v1?+m2v2?

6. Elastic collision : Δp=0; ΔEk=0 {that is, the momentum and kinetic energy of the system are both conserved}

7. Inelastic collision Δp=0; 0<ΔEK<ΔEKm {ΔEK: lost kinetic energy, EKm: lost Maximum kinetic energy}

8. Completely inelastic collision Δp = 0; ΔEK = ΔEKm {joined together into a whole after collision}

9. Object m1 has an initial velocity v1 and is stationary Object m2 has an elastic frontal collision:

v1?=(m1-m2)v1/(m1+m2) v2?=2m1v1/(m1+m2)

10. From 9 The inference obtained -----The exchange speed between the two equal masses during elastic forward collision (conservation of kinetic energy, conservation of momentum)

11. A bullet with horizontal speed vo of m is shot into a long log stationary on a horizontal smooth ground Block M, and the mechanical energy loss when it is embedded in it and moves together

E loss=mvo2/2-(M+m)vt2/2=fs relative {vt: ***same speed, f: resistance, s relative to the displacement of the bullet relative to the long wooden block}

Note:

(1) A head-on collision is also called a center-to-center collision, and the velocity direction is on the line connecting their "centers"; < /p>

(2) The above expressions are all vector operations except for kinetic energy. In one-dimensional cases, they can be transformed into algebraic operations in the positive direction;

(3) Conditions for conservation of momentum in the system: If the external force is zero or the system is not subject to external forces, then the momentum of the system is conserved (collision problem, explosion problem, recoil problem, etc.);

(4) Collision process (extremely short time, system composed of colliding objects) ) is regarded as conservation of momentum, and momentum is conserved when the nucleus decays;

(5) The explosion process is regarded as conservation of momentum, when chemical energy is converted into kinetic energy, and kinetic energy increases; (6) Other related content: recoil motion , rockets, the development of aerospace technology and space navigation [see Volume 1 P128].

7. Work and energy (work is a measure of energy transformation)

1. Work: W = Fscosα (definition formula) {W: work (J), F: constant force (N), s: displacement (m), α: the angle between F and s}

2. Work done by gravity: Wab=mghab {m: mass of the object, g=9.8m/s2≈ 10m/s2, hab: height difference between a and b (hab=ha-hb)}

3. Work done by electric field force: Wab=qUab {q: electric charge (C), Uab: between a and b The potential difference (V) is Uab=φa-φb}

4. Electric power: W=UIt (universal formula) {U: voltage (V), I: current (A), t: power-on time (s)｝

5. Power: P=W/t (definition formula) {P: Power [Watt (W)], W: Work done in t time (J), t: Time spent doing work (s)｝

6. The power of car traction: P = Fv; P level = Fv level {P: instantaneous power, P level: average power}

7 .The car starts with constant power, starts with constant acceleration, and the maximum driving speed of the car (vmax=P amount/f)

8. Electric power: P=UI (universal type) {U: Circuit voltage (V ), I: circuit current (A)}

9. Joule’s Law: Q=I2Rt {Q: Electric heat (J), I: Current intensity (A), R: Resistance value (Ω), t :Power-on time (s)}

10. In a pure resistance circuit, I=U/R; P=UI=U2/R=I2R; Q=W=UIt=U2t/R=I2Rt

11. Kinetic energy: Ek＝mv2/2 {Ek: kinetic energy (J), m: mass of object (kg), v: instantaneous velocity of object (m/s)}

12. Gravity Potential energy: EP=mgh {EP: gravitational potential energy (J), g: gravitational acceleration, h: vertical height (m) (from the zero potential energy surface)}

13. Electric potential energy: EA=qφA {EA: Electric potential energy (J) of the charged body at point A, q: Electric quantity (C), φA: Electric potential (V) at point A (from the zero potential energy surface)}

14. Kinetic energy theorem (When positive work is done on an object, the kinetic energy of the object increases):

W sum = mvt2/2-mvo2/2 or W sum = ΔEK

{W sum: external force does something to the object The total work, ΔEK: kinetic energy change ΔEK=(mvt2/2-mvo2/2)}

15. Law of conservation of mechanical energy: ΔE=0 or EK1+EP1=EK2+EP2 or mv12/2 +mgh1＝mv22/2+mgh2

16. Changes in gravitational work and gravitational potential energy (gravitational work is equal to the negative value of the object’s gravitational potential energy increment) WG＝-ΔEP

Note:

(1) The amount of power indicates the speed of work, and the amount of work indicates the amount of energy conversion;

(2) O0≤α<90O does positive work; 90O<α≤180O does negative work ; α = 90o does not do work (the force does not do work when the direction of the force is perpendicular to the direction of displacement (velocity));

(3) Gravity (elastic force, electric field force, molecular force) does positive work, then gravity (Elastic, electrical, molecular) potential energy decreases

(4) The work done by gravity and the work done by electric field force are independent of the path (see equations 2 and 3); (5) Conditions for the conservation of mechanical energy: except for gravity (elastic force) ) other forces do not do work, but only the conversion between kinetic energy and potential energy; (6) Conversion of other units of energy: 1kWh (degree) = 3.6×106J, 1eV = 1.60×10-19J; * (7) Spring elastic potential energy E =kx2/2, related to stiffness coefficient and deformation amount.

8. Molecular kinetic theory, law of conservation of energy

1. Avogadro’s constant NA=6.02×1023/mol; molecular diameter is on the order of 10-10 meters

2. Oil film method to measure molecular diameter d=V/s {V: volume of single molecule oil film (m3), S: oil film surface area (m)2}

3. Molecular kinetic theory content: Matter is composed of a large number of molecules; a large number of molecules undergo irregular thermal motion; there are interactive forces between molecules.

4. Attraction and repulsion between molecules (1) r < r0, f attraction < f repulsion, F molecular force behaves as repulsion

(2) r = r0, f attraction =f repulsion, F molecular force = 0, E molecular potential energy = Emin (minimum value)

(3)r>r0, f repulsion>f repulsion, F molecular force behaves as gravity

< p>(4)r>10r0, f attraction=f repulsion≈0, F molecular force≈0, E molecular potential energy≈0

5. The first law of thermodynamics W+Q=ΔU{(work sum Heat transfer, these two ways of changing the internal energy of an object are equivalent in effect),

W: the positive work done by the outside world on the object (J), Q: the heat absorbed by the object (J ), ΔU: increased internal energy (J), involving the inability to create the first type of perpetual motion machine [see Volume 2, P40]｝

6. The second law of thermodynamics

Kelvin's statement: It is impossible to transfer heat from a low-temperature object to a high-temperature object without causing other changes (the directionality of heat conduction);

Kelvin's statement: It is impossible to absorb heat from a single heat source and transfer it all Used to do work without causing other changes (the directionality of the conversion of mechanical energy and internal energy) {Involving the second type of perpetual motion machine that cannot be built [see Volume 2 P44]}

7. Thermodynamics III Law: Thermodynamic zero cannot be reached {Lower limit of universe temperature: -273.15 degrees Celsius (thermodynamic zero)}

Note:

(1) Brownian particles are not molecules. The smaller the Brownian particle, the greater the Brownian motion. The more obvious it is, the higher the temperature and the more intense it is;

(2) Temperature is a sign of the average kinetic energy of molecules;

3) The attraction and repulsion between molecules exist at the same time, and with the distance between molecules It decreases as it increases, but the repulsive force decreases faster than the attractive force;

(4) The molecular force does positive work, and the molecular potential energy decreases. At r0, F attraction = F repulsion and the molecular potential energy is minimum; < /p>

(5) When the gas expands, the outside world does negative work W<0 on the gas; as the temperature increases, the internal energy increases ΔU>0; heat is absorbed, Q>0

(6) The internal energy of an object refers to the sum of all the molecular kinetic energy and molecular potential energy of the object. For an ideal gas, the intermolecular force is zero and the molecular potential energy is zero;

(7) r0 is when the molecules are in equilibrium, The distance between molecules;

(8) Other related content: energy conversion and constant law [see Volume 2 P41] / energy development and utilization, environmental protection [see Volume 2 P47] / objects The internal energy, kinetic energy of molecules, and potential energy of molecules [see Volume 2 P47].

9. Properties of gases

1. State parameters of gases:

Temperature: macroscopically, the degree of hotness and coldness of an object; microscopically, the molecules inside an object A sign of the intensity of irregular motion,

The relationship between thermodynamic temperature and Celsius temperature: T=t+273 {T: thermodynamic temperature (K), t: Celsius temperature (℃)}

< p>Volume V: The space that gas molecules can occupy, unit conversion: 1m3=103L=106mL

Pressure p: On a unit area, a large number of gas molecules frequently hit the wall of the container to generate a continuous and uniform pressure. Standard atmospheric pressure: 1atm=1.013×105Pa=76cmHg (1Pa=1N/m2)

2. Characteristics of gas molecular motion: large gaps between molecules; except for the moment of collision, the interaction force is weak; molecular motion The rate is very large

3. The equation of state of an ideal gas: p1V1/T1＝p2V2/T2 {PV/T=constant, T is the thermodynamic temperature (K)}

Note: < /p>

(1) The internal energy of an ideal gas has nothing to do with the volume of the ideal gas, but is related to the temperature and the amount of matter;

(2) The conditions for formula 3 to hold are all ideal gases of a certain mass. , when using the formula, pay attention to the unit of temperature, t is the temperature in degrees Celsius (℃), and T is the thermodynamic temperature (K).

10. Electric field

1. Two kinds of charges, conservation law of charge, elemental charge: (e=1.60×10-19C); the charge of a charged body is equal to an integer multiple of the elemental charge

2. Coulomb’s law: F=kQ1Q2/r2 (in vacuum) {F: force between point charges (N), k: electrostatic force constant k=9.0×109N?m2/C2, Q1, Q2: the amount of electricity (C) of two point charges, r: the distance between two point charges (m), the direction is on their connection line, action force and reaction force, same type of charges repel each other, and different types of charges attract each other}

3. Electric field strength: E=F/q (definition formula, calculation formula) {E: electric field strength (N/C), which is a vector (superposition principle of electric field), q: the amount of test charge (C)｝

4. The electric field formed by the vacuum point (source) charge E=kQ/r2 {r: the distance from the source charge to this position (m), Q: the quantity of the source charge}

5. The field strength of a uniform electric field E=UAB/d {UAB: the voltage between two points AB (V), d: the distance between two points AB in the field strength direction (m)}

6. Electric field force: F=qE {F: Electric field force (N), q: Electricity of the charge subject to the electric field force (C), E: Electric field strength (N/C)}

7. Electric potential and potential difference: UAB=φA-φB, UAB=WAB/q=-ΔEAB/q

8. Electric field force does work: WAB=qUAB=Eqd?WAB: When the charged body goes from A to B Work done by the electric field force (J), q: charge (C), UAB: potential difference (V) between points A and B in the electric field (the work done by the electric field force has nothing to do with the path), E: uniform electric field strength, d :The distance between two points along the direction of field strength (m)}

9. Electric potential energy: EA=qφA {EA: the electric potential energy of the charged body at point A (J), q: electric charge (C), φA: Electric potential (V) at point A}

10. Change in electric potential energy ΔEAB=EB-EA {The difference in electric potential energy when a charged body moves from position A to position B in the electric field}

11. The work done by the electric field force and the change in electric potential energy ΔEAB=-WAB=-qUAB (the increment of the electric potential energy is equal to the negative value of the work done by the electric field force)

12. Capacitance C=Q/U( Definition formula, calculation formula) {C: Capacitance (F), Q: Electricity (C), U: Voltage (potential difference between two plates) (V)}

13. The capacitance of a parallel plate capacitor C = εS /4πkd (S: the area facing the two plates, d: the vertical distance between the two plates, ω: dielectric constant)

Common capacitors [see Volume 2 P111]

14 .Acceleration of charged particles in the electric field (Vo=0): W=ΔEK or qU=mVt2/2, Vt=(2qU/m)1/2

15. The charged particles move along the direction perpendicular to the electric field. Deflection when velocity Vo enters a uniform electric field (without considering the effect of gravity)

Flat vertical electric field direction: uniform linear motion L = Vot (in parallel plates with equal dissimilar charges: E＝U/d)

Throwing motion parallel electric field direction: Uniformly accelerated linear motion with initial velocity of zero d＝at2/2, a＝F/m＝qE/m

Note:

(1) When two identical charged metal balls come into contact, the electric charge distribution rules: the original ones with different charges are neutralized first and then divided equally, and the total amount of the original same charges is divided equally; < /p>

(2) Electric field lines start from positive charges and end at negative charges. The electric field lines do not intersect. The tangent direction is the direction of field strength. The field is strong where the electric field lines are dense. The electric potential becomes lower and lower along the electric field lines. The electric field The lines are perpendicular to the equipotential lines;

(3) The electric field line distribution of common electric fields requires memorization [see figure [Volume 2 P98]];

(4) Electric field intensity (vector ) and electric potential (scalar) are both determined by the electric field itself, and the electric field force and electric potential energy are also related to the amount of electricity carried by the charged body and the positive and negative charges;

(5) A conductor in electrostatic equilibrium is an equipotential body , the surface is an equipotential surface, the electric field lines near the outer surface of the conductor are perpendicular to the conductor surface, the total field strength inside the conductor is zero, there is no net charge inside the conductor, and the net charge is only distributed on the outer surface of the conductor;

( 6) Capacitance unit conversion: 1F＝106μF＝1012PF;

>

(7) Electron volt (eV) is the unit of energy, 1eV=1.60×10-19J;

(8) Other related content: Electrostatic shielding [see Volume 2 P101]/display Wave tubes, oscilloscopes and their applications [See Volume 2 P114] Equipotential surfaces [See Volume 2 P105].

11. Constant current

1. Current intensity: I＝q/t｛I: current intensity (A), q: passing through the cross-load surface of the conductor within time t Electricity (C), t: time (s)}

2. Ohm’s law: I=U/R {I: conductor current intensity (A), U: voltage across the conductor (V), R :Conductor resistance (Ω)｝

3. Resistance, resistance law: R＝ρL/S?ρ: resistivity (Ω·m), L: length of conductor (m), S: conductor Cross-sectional area (m2)}

4. Ohm’s law of closed circuit: I＝E/(r+R) or E＝Ir+IR or E＝U inside + U outside

{I: Total current in the circuit (A), E: Power supply electromotive force (V), R: External circuit resistance (Ω), r: Power supply internal resistance (Ω)}

5. Electrical work and electric power: W=UIt, P=UI?W: Electrical work (J), U: Voltage (V), I: Current (A), t: Time (s), P: Electrical power (W)} < /p>

6. Joule’s law: Q=I2Rt{Q: electric heat (J), I: current through the conductor (A), R: resistance value of the conductor (Ω), t: energization time (s)}

7. In a pure resistance circuit: since I=U/R, W=Q, therefore W=Q=UIt=I2Rt=U2t/R

8. Total power rate of the power supply , power supply output power, power supply efficiency: P total = IE, P out = IU, η = P out/P total {I: total circuit current (A), E: power supply electromotive force (V), U: road terminal voltage (V ), eta: power efficiency}

9. Series/parallel circuit of the circuit Series circuit (P, U and R are proportional) Parallel circuit (P, I and R are inversely proportional)

Resistance relationship (series, parallel and inversion) R series=R1+R2+R3+ 1/R parallel=1/R1+1/R2+1/R3+

Current relationship I total=I1=I2=I3 I And=I1+I2+I3+

Voltage relationship U total=U1+U2+U3+ U total=U1=U2=U3

Power distribution P total=P1+P2+P3+ P Total=P1+P2+P3