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1 BASIC FORMULA IN PHYSICS FOR STUDENTS OF TECHNICAL UNIVERSITIES. Physical foundations of mechanics. Instantaneous speed dr r - radius vector of a material point, t - time, Module of instantaneous speed s - distance along the trajectory, Path length Acceleration: instantaneous tangential normal total τ - unit vector tangent to the trajectory; R is the radius of curvature of the trajectory, n is the unit vector of the main normal. ANGULAR SPEED ds = S t t t d a d a a n n R a a a, n a a a n d φ- angular displacement. Angular acceleration d.. Relationship between linear and.. angular quantities s= φr, υ= ωr, a τ = εr, a n = ω R.3. Impulse.4. of a material point p is the mass of a material point. The basic equation of the dynamics of a material point (Newton's second law)
2 a dp Fi, Fi Law of conservation of momentum for an isolated mechanical system Radius-vector of the center of mass Force of dry friction μ- coefficient of friction, N- force of normal pressure. Elasticity force k- coefficient of elasticity (stiffness), Δl- deformation..4.. Gravitational force F G r and - particle masses, G-gravitational constant, r- distance between particles. Work force A FdS da Power N F Potential energy: k(l) of an elastically deformed body П= gravitational interaction of two particles П= G r of the body in a uniform gravitational field g- gravitational field strength (gravitational acceleration), h- distance from the zero level. P=gh
3.4.4. Gravity tension.4.5. Earth's field g \u003d G (R h) 3 Earth's mass, R 3 - Earth's radius, h - distance from the Earth's surface. Potential of the Earth's gravitational field 3 Kinetic energy of a material point φ= G T= (R 3 3 h) p The law of conservation of mechanical energy for a mechanical system E=T+P=onst Moment of inertia of a material point J=r r- distance to the axis of rotation. Moments of inertia of bodies with a mass about an axis passing through the center of mass: a thin-walled cylinder (ring) of radius R, if the axis of rotation coincides with the axis of the cylinder J o \u003d R, a solid cylinder (disk) of radius R, if the axis of rotation coincides with the axis of the cylinder J o \u003d R ball of radius R J o \u003d 5 R thin rod of length l, if the axis of rotation is perpendicular to the rod J o \u003d l
4 J is the moment of inertia about a parallel axis passing through the center of mass, d is the distance between the axles. Moment of force acting on a material point relative to the origin r-radius-vector of the point of force application Moment of momentum of the system.4.8. about the Z axis r F N.4.9. L z J iz iz i.4.. Basic equation of dynamics.4.. rotary motion Law of conservation of angular momentum for an isolated system Rotational motion dl, J.4.. Σ J i ω i =onst A d Kinetic energy of a rotating body J T= L J Relativistic contraction of length l l lо length of a body at rest c is the speed of light in vacuum. Relativistic time dilation t t t about proper time. Relativistic mass o rest mass Rest energy of the particle E o = o c
5.4.3. Total energy relativistic.4.4. particles.4.5. E=.4.6. Relativistic impulse Р=.4.7. Kinetic energy.4.8. relativistic particle.4.9. T \u003d E- E o \u003d Relativistic relationship between total energy and momentum E \u003d p c + E o and (sign -) or opposite to it directed (sign +) u u u Physics mechanical vibrations and waves. The displacement of the oscillating material point s Aos(t) A is the amplitude of the oscillation, is the natural cyclic frequency, φ o is the initial phase. Cyclic frequency T
6 T oscillation period - frequency Velocity of an oscillating material point Acceleration of an oscillating material point Kinetic energy of a material point making harmonic oscillations v ds d s a v T Potential energy of a material point making harmonic oscillations Ï kx Stiffness coefficient (elasticity factor) Total energy of a material point making harmonic oscillations A sin(t) dv E T П A os(t) A A A sin (t) os (t) d s Differential equation s free harmonic sustained oscillations of magnitude s d s ds Differential equation s of free damped oscillations of magnitude s, - damping coefficient A(t) T Logarithmic decrement ln T A(T t) of damping, relaxation time d s ds Differential equation s F ost , k
7 physical T J, gl - mass of the pendulum, k - spring stiffness, J - moment of inertia of the pendulum, g - free fall acceleration, l - distance from the point of suspension to the center of mass. The equation of a plane wave propagating in the direction of the Ox axis, v is the propagation speed of the wave Wavelength T is the period of the wave, v is the velocity of the wave, the oscillation frequency Wave number The velocity of sound in gases γ is the ratio of the heat capacities of the gas, at constant pressure and volume, R- molar gas constant, T- thermodynamic temperature, M- molar mass gas x (x, t) Aos[ (t) ] v v T v vt v RT Molecular physics and thermodynamics..4.. The amount of substance N N A, N is the number of molecules, N A is the Avogadro constant - the mass of the substance M is the molar mass. Clapeyron-Mendeleev equation p = ν RT,
8 p - gas pressure, - its volume, R - molar gas constant, T - thermodynamic temperature. The equation of the molecular-kinetic theory of gases Р= 3 n<εпост >= 3 no<υ кв >n is the concentration of molecules,<ε пост >is the average kinetic energy of the translational motion of the molecule. o is the mass of the molecule<υ кв >- RMS speed. Average energy of a molecule<ε>= i kt i - number of degrees of freedom k - Boltzmann's constant. Internal energy ideal gas U= i νrt Molecular velocities: root mean square<υ кв >= 3kT = 3RT ; arithmetic mean<υ>= 8 8RT = kt ; most likely<υ в >= Average free length kt = RT ; molecular range d-effective diameter of the molecule Average number of collisions (d n) of the molecule per unit time z d n v
9 Distribution of molecules in a potential field of forces P-potential energy of a molecule. Barometric formula p - gas pressure at height h, p - gas pressure at a level taken as zero, - mass of the molecule, Fick's law of diffusion j - mass flow density, n n exp kt gh p p exp kt j d ds d =-D dx d - density gradient, dx D-diffusion coefficient, ρ-density, d-gas mass, ds-elementary area perpendicular to the Ox axis. Fourier thermal conductivity law j - heat flux density, Q j Q dq ds dt =-æ dx dt - temperature gradient, dx æ - thermal conductivity coefficient, Internal friction force η - dynamic viscosity coefficient, dv df ds dz d - velocity gradient, dz Coefficient diffusion D= 3<υ><λ>Coefficient of dynamic viscosity (internal friction) v 3 D Coefficient of thermal conductivity æ = 3 сv ρ<υ><λ>=ηс v
10 s v specific isochoric heat capacity, Molar heat capacity of ideal gas isochoric isobaric First law of thermodynamics i C v R i C p R dq=du+da, da=pd, du=ν C v dt -)= ν R(T -T) isothermal p А= ν RT ln = ν RT ln p adiabatic A C T T) γ=с р /С v (RT A () p A= () Poisson's equations Efficiency of the Carnot cycle. 4.. Q n and T n - the amount of heat received from the heater and its temperature; Q x and T x - the amount of heat transferred to the refrigerator and its temperature. Change in entropy during the transition of the system from state to state P γ =onst T γ- =onst T γ r - γ =onst Qí Q Q S S í õ Tí T T dq T í õ
Examples of problem solving Example 6 One end of a thin homogeneous rod with a length is rigidly fixed on the surface of a homogeneous ball so that the centers of mass of the rod and the ball, as well as the attachment point, are on the same
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Absolutely necessary so that a person who decides to study this science, armed with them, can feel in the world of physics like a fish in water. Without knowing the formulas, it is unthinkable to solve problems in physics. But it is almost impossible to remember all the formulas and it is important to know, especially for a young mind, where to find this or that formula and when to apply it.
The location of physical formulas in specialized textbooks is usually distributed among the corresponding sections among text information, so searching for them there can take quite a lot of time, and even more so if you suddenly need them urgently!
Presented below physics cheat sheets contain all the basic formulas from the course of physics that will be useful to students of schools and universities.
All formulas school course in physics from the site http://4ege.ru
I. Kinematics download
1. Basic concepts
2. Laws of addition of velocities and accelerations
3. Normal and tangential accelerations
4. Types of movements
4.1. Uniform movement
4.1.1. Uniform rectilinear motion
4.1.2. Uniform circular motion
4.2. Movement with constant acceleration
4.2.1. Uniformly accelerated motion
4.2.2. Uniformly slow motion
4.3. harmonic movement
II. Dynamics download
1. Newton's second law
2. The theorem on the motion of the center of mass
3. Newton's third law
4. Forces
5. Gravitational force
6. Forces acting through contact
III. Conservation laws. Work and power download
1. Momentum of a material point
2. Momentum of the system of material points
3. Theorem on the change in momentum of a material point
4. Theorem on the change in the momentum of a system of material points
5. Law of conservation of momentum
6. Work force
7. Power
8. Mechanical energy
9. Mechanical energy theorem
10. Law of conservation of mechanical energy
11. Dissipative forces
12. Methods for calculating work
13. Time Average Force
IV. Download statics and hydrostatics
1. Equilibrium conditions
2. Torque
3. Unstable balance, stable balance, indifferent balance
4. Center of mass, center of gravity
5. Force of hydrostatic pressure
6. Fluid pressure
7. Pressure at any point in the liquid
8, 9. Pressure in a homogeneous fluid at rest
10. Archimedean force
V. Thermal phenomena download
1. Mendeleev-Clapeyron equation
2. Dalton's Law
3. Basic equation of the MKT
4. Gas laws
5. First law of thermodynamics
6. Adiabatic process
7. Efficiency of a cyclic process (heat engine)
8. Saturated steam
VI. Electrostatics download
1. Coulomb's law
2. Principle of superposition
3. Electric field
3.1. Tension and Potential electric field, created by one point charge Q
3.2. The intensity and potential of the electric field created by a system of point charges Q1, Q2, ...
3.3. The intensity and potential of the electric field created by a ball uniformly charged over the surface
3.4. Strength and potential of a uniform electric field (created by a uniformly charged plane or a flat capacitor)
4. Potential energy of a system of electric charges
5. Electricity
6. Properties of a conductor in an electric field
VII. DC download
1.Ordered speed
2. Current
3. Current density
4. Ohm's law for a circuit section that does not contain EMF
5. Ohm's law for a circuit section containing EMF
6. Ohm's law for a complete (closed) circuit
7. Series connection of conductors
8. Parallel connection of conductors
9. Work and power electric current
10. Efficiency of the electrical circuit
11. The condition for the allocation of maximum power to the load
12. Faraday's law for electrolysis
VIII. Magnetic phenomena download
1. Magnetic field
2. Movement of charges in a magnetic field
3. Frame with current in a magnetic field
4. Magnetic fields created by various currents
5. Interaction of currents
6. The phenomenon of electromagnetic induction
7. The phenomenon of self-induction
IX. Oscillations and waves download
1. Fluctuations, definitions
2. Harmonic vibrations
3. The simplest oscillatory systems
4. Wave
X. Optics download
1. Law of reflection
2. Law of refraction
3. Lens
4. Image
5. Possible cases of the location of the subject
6. Interference
7. Diffraction
Big physics cheat sheet. All formulas are presented in a compact form with a few comments. The cheat sheet also contains useful constants and other information. The file contains the following sections of physics:
Mechanics (kinematics, dynamics and statics)
Molecular physics. Properties of gases and liquids
Thermodynamics
Electrical and electromagnetic phenomena
Electrodynamics. D.C
Electromagnetism
Vibrations and waves. Optics. Acoustics
Quantum physics and the theory of relativity
Small spur on physics. Everything you need for the exam. Cutting the basic formulas in physics on one page. Not very aesthetically pleasing, but practical. :-)
Good day dear radio amateurs!
I welcome you to the site ""
Formulas form the backbone of electronics science. Instead of dumping a whole bunch of radio elements on the table, and then reconnecting them together, trying to figure out what will come into being as a result, experienced specialists immediately build new circuits based on known mathematical and physical laws. It is the formulas that help determine the specific values of the ratings of electronic components and the operating parameters of the circuits.
In the same way, it is effective to use formulas to modernize ready-made circuits. For example, in order to select the correct resistor in a circuit with a light bulb, you can apply basic law Ohm for direct current (you can read about it in the Ohm's Law Relations section immediately after our lyrical introduction). The light bulb can be made, thus, to shine more brightly or, conversely, to dim.
In this chapter, many of the basic formulas of physics will be given, which one has to face sooner or later in the process of working in electronics. Some of them have been known for centuries, but we still continue to use them successfully, as will our grandchildren.
Ohm's Law Relationships
Ohm's law is the relationship between voltage, current, resistance and power. All derived formulas for calculating each of the indicated quantities are presented in the table:
This table uses the following generally accepted notation for physical quantities:
U- voltage (V),
I- current (A),
R- Power, W),
R- resistance (Ohm),
Let's practice on the following example: let's find the power of the circuit. It is known that the voltage at its terminals is 100 V, and the current is 10 A. Then the power, according to Ohm's law, will be 100 x 10 = 1000 W. The resulting value can be used to calculate, say, the fuse rating that needs to be inserted into the device, or, for example, to estimate the electricity bill that the electrician from the housing office will personally bring to you at the end of the month.
And here's another example: let's find out the value of the resistor in the circuit with a light bulb, if we know what current we want to pass through this circuit. According to Ohm's law, the current is:
I=U/R
A circuit consisting of a light bulb, a resistor and a power source (battery) is shown in the figure. Using the above formula, even a schoolboy can calculate the desired resistance.
What is in this formula? Let's take a closer look at variables.
> U pet(sometimes also referred to as V or E): supply voltage. Due to the fact that when current passes through the light bulb, some voltage drops on it, the magnitude of this drop (usually the operating voltage of the light bulb, in our case 3.5 V) must be subtracted from the power supply voltage. For example, if Upit \u003d 12 V, then U \u003d 8.5 V, provided that 3.5 V drops on the light bulb.
> I: The current (measured in amps) that is going to flow through the light bulb. In our case, 50 mA. Since the current is indicated in the formula in amperes, 50 milliamps is only a small part of it: 0.050 A.
> R: the desired resistance of the current-limiting resistor, in ohms.
In continuation, you can put real numbers in the resistance calculation formula instead of U, I and R:
R \u003d U / I \u003d 8.5 V / 0.050 A \u003d 170 Ohm
Resistance calculations
Calculating the resistance of one resistor in a simple circuit is quite simple. However, with the addition of other resistors, in parallel or in series, the total resistance of the circuit also changes. The total resistance of several resistors connected in series is equal to the sum of the individual resistances of each of them. For a parallel connection, things are a little more complicated.
Why should you pay attention to how the components are connected to each other? There are several reasons for that.
> Resistors are only a certain fixed number of values. In some circuits, the resistance value must be calculated exactly, but since a resistor of exactly this value may not exist at all, it is necessary to connect several elements in series or in parallel.
> Resistors are not the only components that have resistance. For example, the windings of an electric motor also have some current resistance. In many practical tasks you have to calculate the total resistance of the entire circuit.
Calculation of the resistance of series resistors
The formula for calculating the total resistance of resistors connected in series is obscenely simple. You just need to add up all the resistances:
Rtot = Rl + R2 + R3 + ... (as many times as there are elements)
In this case, the values Rl, R2, R3 and so on are the resistances of individual resistors or other components of the circuit, and Rtot is the resulting value.
So, for example, if there is a circuit of two resistors connected in series with nominal values of 1.2 and 2.2 kOhm, then the total resistance of this section of the circuit will be 3.4 kOhm.
Parallel Resistors Calculation
Things get a little more complicated if you want to calculate the resistance of a circuit consisting of parallel resistors. The formula takes the form:
Rtot = R1 * R2 / (R1 + R2)
where R1 and R2 are the resistances of individual resistors or other circuit elements, and Rtot is the resulting value. So, if we take the same resistors with ratings of 1.2 and 2.2 kOhm, but connected in parallel, we get
776,47 = 2640000 / 3400
To calculate the resulting resistance of an electrical circuit of three or more resistors, the following formula is used:
Capacity calculations
The formulas given above are also valid for calculating capacities, only exactly the opposite. Just like resistors, they can be extended to any number of components in a circuit.
Calculation of capacitance of parallel capacitors
If you need to calculate the capacitance of a circuit consisting of parallel capacitors, you just need to add their values:
Сtot \u003d CI + C2 + SZ + ...
In this formula, CI, C2 and C3 are the capacitances of individual capacitors, and Ctot is a summing value.
Calculation of capacitance of series capacitors
To calculate the total capacitance of a pair of capacitors connected in series, the following formula is used:
Сtot \u003d C1 * C2 / (C1 + C2)
where C1 and C2 are the capacitance values of each of the capacitors, and Ctot is the total capacitance of the circuit
Calculation of the capacitance of three or more capacitors connected in series
Are there any capacitors in the circuit? A lot of? It's okay: even if they are all connected in series, you can always find the resulting capacitance of this circuit:
So why knit several capacitors in series at once when one could be enough? One of the logical explanations for this fact is the need to obtain a specific circuit capacitance rating, which has no analogue in the standard range of ratings. Sometimes you have to go on a more thorny path, especially in sensitive circuits, such as radio receivers.
Calculation of energy equations
The most widely used unit of energy in practice is kilowatt-hours or, if it concerns electronics, watt-hours. You can calculate the energy expended by the circuit by knowing the length of time during which the device is turned on. The formula for calculating is:
watt hours = P x T
In this formula, the letter P denotes the power consumption, expressed in watts, and T is the operating time in hours. In physics, it is customary to express the amount of energy expended in watt-seconds, or Joules. To calculate energy in these units, watt-hours are divided by 3600.
Calculation of the constant capacity of the RC chain
Electronic circuits often use RC circuits to provide time delays or lengthening of pulsed signals. The simplest circuits consist of just a resistor and a capacitor (hence the origin of the term RC circuit).
The principle of operation of an RC circuit is that a charged capacitor is discharged through a resistor not instantly, but over a certain period of time. The greater the resistance of the resistor and / or capacitor, the longer it will take to discharge the capacitance. Circuit designers often use RC circuits to create simple timers and oscillators or to change waveforms.
How can you calculate the time constant of an RC circuit? Because this circuit consists of a resistor and a capacitor, the equation uses the resistance and capacitance values. Typical capacitors have a capacitance of the order of microfarads and even less, and farads are the system units, so the formula operates with fractional numbers.
T=RC
In this equation, T is the time in seconds, R is the resistance in ohms, and C is the capacitance in farads.
Suppose, for example, there is a 2000 ohm resistor connected to a 0.1 uF capacitor. The time constant of this chain will be 0.002 s, or 2 ms.
In order to make it easier for you at first to convert ultra-small capacitance units to farads, we have compiled a table:
Frequency and Wavelength Calculations
The frequency of a signal is inversely proportional to its wavelength, as will be seen from the formulas below. These formulas are especially useful when working with radio electronics, for example, to estimate the length of a piece of wire that is planned to be used as an antenna. In all of the following formulas, wavelength is expressed in meters and frequency is expressed in kilohertz.
Signal frequency calculation
Suppose you want to study electronics so that you can build your own transceiver and chat with fellow enthusiasts from another part of the world over an amateur radio network. The frequencies of radio waves and their length are in the formulas side by side. In amateur radio networks, you can often hear statements that the operator works on such and such a wavelength. Here's how to calculate the frequency of a radio signal given the wavelength:
Frequency = 300000 / wavelength
The wavelength in this formula is expressed in millimeters, not feet, arshins, or parrots. The frequency is given in megahertz.
Signal Wavelength Calculation
The same formula can be used to calculate the wavelength of a radio signal if its frequency is known:
Wavelength = 300000 / Frequency
The result will be expressed in millimeters, and the frequency of the signal is indicated in megahertz.
Let's give an example of calculation. Let a radio amateur communicate with his friend at a frequency of 50 MHz (50 million periods per second). Substituting these numbers into the above formula, we get:
6000 millimeters = 300000/ 50 MHz
However, more often they use system units of length - meters, therefore, to complete the calculation, it remains for us to translate the wavelength into a more understandable value. Since there are 1000 millimeters in 1 meter, the result will be 6 m. It turns out that the radio amateur tuned his radio station to a wavelength of 6 meters. Cool!
Definition 1
Physics is natural science, which studies the general and fundamental laws of the structure and evolution of the material world.
Importance of physics in modern world huge. Her new ideas and achievements lead to the development of other sciences and new scientific discoveries, which, in turn, are used in technology and industry. For example, discoveries in the field of thermodynamics made it possible to build a car, and the development of radio electronics led to the emergence of computers.
Despite the incredible amount of accumulated knowledge about the world, human understanding of processes and phenomena is constantly changing and developing, new research leads to new and unresolved issues that require new explanations and theories. In this sense, physics is in a continuous process of development and is still far from being able to explain everything. natural phenomena and processes.
All formulas for $7$ class
Uniform motion speed
All formulas for grade 8
The amount of heat during heating (cooling)
$Q$ - amount of heat [J], $m$ - mass [kg], $t_1$ - initial temperature, $t_2$ - final temperature, $c$ - specific heat
The amount of heat during fuel combustion
$Q$ – quantity of heat [J], $m$ – mass [kg], $q$ – specific heat of combustion of fuel [J/kg]
The amount of heat of fusion (crystallization)
$Q=\lambda \cdot m$
$Q$ – amount of heat [J], $m$ – mass [kg], $\lambda$ – specific heat of fusion [J/kg]
Heat engine efficiency
$efficiency=\frac(A_n\cdot 100%)(Q_1)$
Efficiency - efficiency [%], $A_n$ - useful work [J], $Q_1$ - amount of heat from the heater [J]
Current strength
$I$ - current [A], $q$ - electric charge [C], $t$ - time [s]
electrical voltage
$U$ - voltage [V], $A$ - work [J], $q$ - electric charge [C]
Ohm's law for a circuit section
$I$ - current [A], $U$ - voltage [V], $R$ - resistance [Ohm]
Serial connection of conductors
Parallel connection of conductors
$\frac(1)(R)=\frac(1)(R_1) +\frac(1)(R_2)$
Electric current power
$P$ - power [W], $U$ - voltage [V], $I$ - current [A]
Cheat sheet with formulas in physics for the exam
and not only (may need 7, 8, 9, 10 and 11 classes).
For starters, a picture that can be printed in a compact form.
Mechanics
- Pressure P=F/S
- Density ρ=m/V
- Pressure at the depth of the liquid P=ρ∙g∙h
- Gravity Ft=mg
- 5. Archimedean force Fa=ρ w ∙g∙Vt
- Equation of motion for uniformly accelerated motion
X=X0 + υ 0∙t+(a∙t 2)/2 S=( υ 2 -υ 0 2) /2а S=( υ +υ 0) ∙t /2
- Velocity equation for uniformly accelerated motion υ =υ 0 +a∙t
- Acceleration a=( υ -υ 0)/t
- Circular speed υ =2πR/T
- Centripetal acceleration a= υ 2/R
- Relationship between period and frequency ν=1/T=ω/2π
- Newton's II law F=ma
- Hooke's law Fy=-kx
- Law of universal gravitation F=G∙M∙m/R 2
- The weight of a body moving with acceleration a P \u003d m (g + a)
- The weight of a body moving with acceleration a ↓ P \u003d m (g-a)
- Friction force Ffr=µN
- Body momentum p=m υ
- Force impulse Ft=∆p
- Moment M=F∙ℓ
- Potential energy of a body raised above the ground Ep=mgh
- Potential energy of elastically deformed body Ep=kx 2 /2
- Kinetic energy of the body Ek=m υ 2 /2
- Work A=F∙S∙cosα
- Power N=A/t=F∙ υ
- Efficiency η=Ap/Az
- Oscillation period mathematical pendulum T=2π√ℓ/g
- Oscillation period of a spring pendulum T=2 π √m/k
- The equation harmonic vibrationsХ=Хmax∙cos ωt
- Relationship of the wavelength, its speed and period λ= υ T
Molecular physics and thermodynamics
- Amount of substance ν=N/ Na
- Molar mass M=m/ν
- Wed. kin. energy of monatomic gas molecules Ek=3/2∙kT
- Basic equation of MKT P=nkT=1/3nm 0 υ 2
- Gay-Lussac law (isobaric process) V/T =const
- Charles' law (isochoric process) P/T =const
- Relative humidity φ=P/P 0 ∙100%
- Int. ideal energy. monatomic gas U=3/2∙M/µ∙RT
- Gas work A=P∙ΔV
- Boyle's law - Mariotte (isothermal process) PV=const
- The amount of heat during heating Q \u003d Cm (T 2 -T 1)
- The amount of heat during melting Q=λm
- The amount of heat during vaporization Q=Lm
- The amount of heat during fuel combustion Q=qm
- The equation of state for an ideal gas is PV=m/M∙RT
- First law of thermodynamics ΔU=A+Q
- Efficiency of heat engines η= (Q 1 - Q 2) / Q 1
- Ideal efficiency. engines (Carnot cycle) η \u003d (T 1 - T 2) / T 1
Electrostatics and electrodynamics - formulas in physics
- Coulomb's law F=k∙q 1 ∙q 2 /R 2
- Electric field strength E=F/q
- Email tension. field of a point charge E=k∙q/R 2
- Surface charge density σ = q/S
- Email tension. fields of the infinite plane E=2πkσ
- Dielectric constant ε=E 0 /E
- Potential energy of interaction. charges W= k∙q 1 q 2 /R
- Potential φ=W/q
- Point charge potential φ=k∙q/R
- Voltage U=A/q
- For a uniform electric field U=E∙d
- Electric capacity C=q/U
- Capacitance of a flat capacitor C=S∙ ε ∙ε 0/d
- Energy of a charged capacitor W=qU/2=q²/2С=CU²/2
- Current I=q/t
- Conductor resistance R=ρ∙ℓ/S
- Ohm's law for the circuit section I=U/R
- The laws of the last compounds I 1 \u003d I 2 \u003d I, U 1 + U 2 \u003d U, R 1 + R 2 \u003d R
- Parallel laws. conn. U 1 \u003d U 2 \u003d U, I 1 + I 2 \u003d I, 1 / R 1 + 1 / R 2 \u003d 1 / R
- Electric current power P=I∙U
- Joule-Lenz law Q=I 2 Rt
- Ohm's law for a complete chain I=ε/(R+r)
- Short circuit current (R=0) I=ε/r
- Magnetic induction vector B=Fmax/ℓ∙I
- Ampere Force Fa=IBℓsin α
- Lorentz force Fл=Bqυsin α
- Magnetic flux Ф=BSсos α Ф=LI
- Law of electromagnetic induction Ei=ΔФ/Δt
- EMF of induction in moving conductor Ei=Вℓ υ sinα
- EMF of self-induction Esi=-L∙ΔI/Δt
- The energy of the magnetic field of the coil Wm \u003d LI 2 / 2
- Oscillation period count. contour T=2π ∙√LC
- Inductive reactance X L =ωL=2πLν
- Capacitance Xc=1/ωC
- The current value of the current Id \u003d Imax / √2,
- RMS voltage Ud=Umax/√2
- Impedance Z=√(Xc-X L) 2 +R 2
Optics
- The law of refraction of light n 21 \u003d n 2 / n 1 \u003d υ 1 / υ 2
- Refractive index n 21 =sin α/sin γ
- Thin lens formula 1/F=1/d + 1/f
- Optical power of the lens D=1/F
- max interference: Δd=kλ,
- min interference: Δd=(2k+1)λ/2
- Differential grating d∙sin φ=k λ
The quantum physics
- Einstein's formula for the photoelectric effect hν=Aout+Ek, Ek=U ze
- Red border of the photoelectric effect ν to = Aout/h
- Photon momentum P=mc=h/ λ=E/s
Physics of the atomic nucleus
