All formulas for university physics tables. Physics formulas that are recommended to be learned and mastered to successfully pass the Unified State Exam. Basic laws of physics that a person should know

Mechanics 1. Pressure P=F/S 2. Density ρ=m/V 3. Pressure at the depth of the liquid P=ρ∙g∙h 4. Gravity Ft=mg 5. Archimedean force Fa=ρl∙g∙Vt 6. Equation of motion for uniformly accelerated motion m(g+a) m(ga) X=X0+υ0∙t+(a∙t2)/2 S= (υ2υ0 2) /2а S= (υ+υ0) ∙t /2 7. Velocity equation for uniformly accelerated motion υ=υ0+a∙t 8. Acceleration a=(υυ 0)/t 9. Speed ​​when moving in a circle υ=2πR/T 10. Centripetal acceleration a=υ2/R 11. Relationship between period and frequency ν=1/T=ω/2π 12. Newton’s II law F=ma 13. Hooke’s law Fy=kx 14. Law of Universal Gravitation F=G∙M∙m/R2 15. Weight of a body moving with acceleration a P= 16 . Weight of a body moving with acceleration a P = 17. Friction force Ftr = µN 18. Impulse of the body p = mυ 19. Impulse of force Ft = ∆p 20. Moment of force M = F∙? 21. Potential energy of a body raised above the ground Ep=mgh 22. Potential energy of an elastically deformed body Ep=kx2/2 23. Kinetic energy of a body Ek=mυ2/2 24. Work A=F∙S∙cosα 25. Power N=A /t=F∙υ 26. Efficiency η=Ap/Az 27. Period of oscillation of a mathematical pendulum T=2 √?/π 28. Period of oscillation of a spring pendulum T=2 29. Equation of harmonic oscillations Х=Хmax∙cos 30. Relationship between wavelength, its speed and period λ= υТ Molecular physics and thermodynamics 31. Amount of substance ν=N/ Na 32. Molar mass 33. Avg. kin. energy of molecules of a monatomic gas Ek=3/2∙kT 34. Basic equation of MKT P=nkT=1/3nm0υ2 35. Gay-Lussac’s law (isobaric process) V/T =const 36. Charles’s law (isochoric process) P/T = const 37. Relative humidity φ=P/P0∙100% 38. Int. energy ideal. monatomic gas U=3/2∙M/µ∙RT 39. Gas work A=P∙ΔV 40. Boyle’s law – Mariotte (isothermal process) PV=const 41. Amount of heat during heating Q=Cm(T2T1) g √π m/k tω ↓ М=m/ν Optics 86. Law of light refraction n21=n2/n1= υ 1/ υ 2 87. Refractive index n21=sin α/sin γ 88. Thin lens formula 1/F=1/d + 1/f 89. Lens optical power D=1/F 90. max interference: Δd=kλ, 91. min interference: Δd=(2k+1)λ/2 92. Differential grating d∙sin φ=k λ Quantum physics 93. Einstein's flag for the photoelectric effect hν=Aout+Ek, Ek=Uзе 94. Red boundary of the photoelectric effect νк = Aout/h 95. Photon momentum P=mc=h/ λ=E/s Physics of the atomic nucleus 96. Law of radioactive decay N=N0∙2t/T 97. Binding energy of atomic nuclei ECB=(Zmp+NmnМя)∙c2 SRT t=t1/√1υ2/c2 98. 99. ?=?0∙√1υ2/c2 100. υ2 =(υ1+υ)/1+ υ1∙υ/c2 101. E = mс2 42. Amount of heat during melting Q= mλ 43. Amount of heat during vaporization Q=Lm 44. Amount of heat during fuel combustion Q=qm 45. Equation of state of an ideal gas PV=m/M∙RT 46. The first law of thermodynamics ΔU=A+Q 47. Efficiency of heat engines = (η Q1 Q2)/ Q1 48. Efficiency ideal. engines (Carnot cycle) = (Тη 1 Т2)/ Т1 Electrostatics and electrodynamics 49. Coulomb's law F=k∙q1∙q2/R2 50. Electric field strength E=F/q 51. Electric field strength. field of a point charge E=k∙q/R2 52. Surface charge density σ = q/S 53. Electrical strength. fields of an infinite plane E=2 kπ σ 54. Dielectric constant ε=E0/E 55. Potential energy of interaction. charges W= k∙q1q2/R 56. Potential φ=W/q 57. Point charge potential =φ k∙q/R 58. Voltage U=A/q ​​59. For a uniform electric field U=E∙d 60. Electric capacity C=q/U 61. Electrical capacity of a flat capacitor C=S∙ε∙ε0/d 62. Energy of a charged capacitor W=qU/2=q²/2С=CU²/2 63. Current strength I=q/t 64. Conductor resistance R=ρ∙?/S 65. Ohm's law for the circuit section I=U/R 66. Laws of sequence. connections I1=I2=I, U1+U2=U, R1+R2=R 67. Parallel laws. conn. U1=U2=U, I1+I2=I, 1/R1+1/R2=1/R 68. Electric current power P=I∙U 69. Joule-Lenz’s law Q=I2Rt 70. Ohm’s law for a complete circuit I=ε /(R+r) 71. Short circuit current (R=0) I=ε/r 72. Magnetic induction vector B=Fmax/?∙I 73. Ampere force Fa=IB?sin α 74. Lorentz force Fl=Bqυsin α 75. Magnetic flux Ф=BSсos α Ф=LI 76. Law of electromagnetic induction Ei=ΔФ/Δt 77. Induction emf in a moving conductor Ei=В?υsinα 78. Self-induction emf Esi=L∙ΔI/Δt 79. Magnetic field energy coil Wm=LI2/2 80. Oscillation period no. circuit T=2 ∙√π LC 81. Inductive reactance XL= Lω =2 Lπ ν 82. Capacitive reactance Xc=1/ Cω 83. Effective value of current Id=Imax/√2, 84. Effective value of voltage Ud=Umax/ √2 85. Impedance Z=√(XcXL)2+R2

Good afternoon, dear radio amateurs!
Welcome to the website ““

The formulas form the skeleton of the science of electronics. Instead of dumping a whole bunch of radio elements on the table and then reconnecting them together, trying to figure out what will be born 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 operating parameters of circuits.

It is just as 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 the basic Ohm’s law for direct current (you can read about it in the section “Relationships of Ohm’s Law” immediately after our lyrical introduction). The light bulb can thus be made to shine more brightly or, conversely, dimmed.

This chapter will present many basic physics formulas that sooner or later you will encounter while 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 relations

Ohm's Law is the relationship between voltage, current, resistance and power. All derived formulas for calculating each of these values ​​are presented in the table:

This table uses the following generally accepted designations for physical quantities:

U- voltage (V),

I- current (A),

R- power (W),

R- resistance (Ohm),

Let's practice using the following example: let's say we need to 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 equal to 100 x 10 = 1000 W. The obtained value can be used to calculate, say, the fuse rating that needs to be entered into the device, or, for example, to estimate the electricity bill that an electrician from the housing office will personally bring to you at the end of the month.

Here's another example: let's say we need to find out the value of the resistor in a 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 equal to:

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 schoolchild can calculate the required resistance.

What is what in this formula? Let's take a closer look at the variables.

> U pit(sometimes also written as V or E): supply voltage. Due to the fact that when current passes through the light bulb, some voltage drops across 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 voltage of the power source. For example, if Up = 12 V, then U = 8.5 V, provided that 3.5 V drops across the light bulb.

> I: The current (measured in amperes) that is planned to flow through the light bulb. In our case - 50 mA. Since the current in the formula is indicated 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 formula for calculating resistance instead of U, I and R:

R = U/I = 8.5 V / 0.050 A = 170 Ohm

Resistance calculations

Calculating the resistance of one resistor in a simple circuit is quite simple. However, as other resistors are added to it, either in parallel or in series, the overall 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, everything is a little more complicated.

Why do you need to pay attention to the way components are connected to each other? There are several reasons for this.

> Resistor resistances are only a certain fixed range of values. In some circuits, the resistance value must be calculated accurately, but since a resistor of exactly this value may not exist at all, several elements must be connected in series or in parallel.

> Resistors are not the only components that have resistance. For example, the turns of an electric motor winding also have some resistance to current. In many practical problems, it is necessary 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 indecently simple. You just need to add up all the resistances:

Rtotal = 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 circuit components, and Rtotal is the resulting value.

So, for example, if there is a circuit of two resistors connected in series with values ​​of 1.2 and 2.2 kOhm, then the total resistance of this section of the circuit will be equal to 3.4 kOhm.

Calculation of the resistance of parallel resistors

Things get a little more complicated if you need to calculate the resistance of a circuit consisting of parallel resistors. The formula takes the form:

R total = 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 values ​​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, use the following formula:

Capacity calculations

The formulas given above are also valid for calculating capacities, only exactly the opposite. Just like resistors, they can be extended to cover any number of components in a circuit.

Calculation of the capacitance of parallel capacitors

If you need to calculate the capacitance of a circuit consisting of parallel capacitors, you simply need to add their values:

Commun = CI + C2 + SZ + ...

In this formula, CI, C2 and SZ are the capacitances of individual capacitors, and Ctot is a summing value.

Calculation of the capacitance of series capacitors

To calculate the total capacitance of a pair of capacitors connected in series, the following formula is used:

Commun = C1 * C2 / (C1 + C2)

where C1 and C2 are the capacitance values ​​of each capacitor, and Ctot is the total capacitance of the circuit

Calculation of the capacitance of three or more series-connected capacitors

Are there capacitors in the circuit? Many? It's okay: even if they are all connected in series, you can always find the resulting capacitance of this circuit:

So why connect several capacitors in series at once when one could suffice? One of the logical explanations for this fact is the need to obtain a specific value for the circuit capacitance, which has no analogue in the standard series of ratings. Sometimes you have to go down a more thorny path, especially in sensitive circuits such as radio receivers.

Calculation of energy equations

The most widely used unit of energy measurement in practice is kilowatt-hours or, in the case of 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 calculation is:

watt hours = P x T

In this formula, the letter P denotes 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 constant capacitance of an RC circuit

Electronic circuits often use RC circuits to provide time delays or lengthen pulse signals. The simplest circuits consist of just a resistor and a capacitor (hence the origin of the term RC circuit).

The operating principle 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 the capacitance will take to discharge. Circuit designers very often use RC circuits to create simple timers and oscillators or alter waveforms.

How can you calculate the time constant of an RC circuit? Since this circuit consists of a resistor and a capacitor, the resistance and capacitance values ​​are used in the equation. Typical capacitors have a capacitance on the order of microfarads or even less, and the system units are farads, so the formula operates in fractional numbers.

T=RC

In this equation, T stands for time in seconds, R stands for resistance in ohms, and C stands for capacitance in farads.

Let, for example, have a 2000 ohm resistor connected to a 0.1 µF capacitor. The time constant of this chain will be equal to 0.002 s, or 2 ms.

In order to make it easier for you at first to convert ultra-small units of capacitance into farads, we have compiled a table:

Frequency and wavelength calculations

The frequency of a signal is a quantity 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, for estimating the length of a piece of wire that is planned to be used as an antenna. In all the following formulas, wavelength is expressed in meters and frequency in kilohertz.

Signal frequency calculation

Suppose you want to study electronics in order to build your own transceiver and chat with similar enthusiasts from another part of the world on an amateur radio network. The frequencies of radio waves and their length stand side by side in the formulas. 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, and not in 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 signal frequency is indicated in megahertz.

Let's give an example of a calculation. Let a radio amateur communicate with his friend on a frequency of 50 MHz (50 million cycles 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, so to complete the calculation we just have to convert the wavelength into a more understandable value. Since there are 1000 millimeters in 1 meter, the result is 6 m. It turns out that the radio amateur tuned his radio station to a wavelength of 6 meters. Cool!

Definition 1

Physics is a natural science that studies the general and fundamental laws of the structure and evolution of the material world.

The importance of physics in the modern world is enormous. Its 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 make it possible to build a car, and the development of radio electronics led to the advent 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 the emergence of new and unresolved questions 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 all natural phenomena and processes.

All formulas for $7$ class

Uniform speed

All formulas for 8th grade

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 capacity

The amount of heat during fuel combustion

$Q$ – amount of heat [J], $m$ – mass [kg], $q$ – ​​specific heat of fuel combustion [J/kg]

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 factor [%], $A_n$ – useful work [J], $Q_1$ – amount of heat from the heater [J]

Current strength

$I$ – current strength [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]

Series 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]

In order to successfully prepare for the CT in physics and mathematics, among other things, it is necessary to fulfill three most important conditions:

1. Study all topics and complete all tests and assignments given in the educational materials on this site. To do this, you need nothing at all, namely: devote three to four hours every day to preparing for the CT in physics and mathematics, studying theory and solving problems. The fact is that the CT is an exam where it is not enough just to know physics or mathematics, you also need to be able to quickly and without failures solve a large number of problems on different topics and of varying complexity. The latter can only be learned by solving thousands of problems.
2. Learn all the formulas and laws in physics, and formulas and methods in mathematics. In fact, this is also very simple to do; there are only about 200 necessary formulas in physics, and even a little less in mathematics. In each of these subjects there are about a dozen standard methods for solving problems of a basic level of complexity, which can also be learned, and thus, completely automatically and without difficulty solving most of the CT at the right time. After this, you will only have to think about the most difficult tasks.
3. Attend all three stages of rehearsal testing in physics and mathematics. Each RT can be visited twice to decide on both options. Again, on the CT, in addition to the ability to quickly and efficiently solve problems, and knowledge of formulas and methods, you must also be able to properly plan time, distribute forces, and most importantly, fill out the answer form correctly, without confusing the numbers of answers and problems, or your own last name. Also, during RT, it is important to get used to the style of asking questions in problems, which may seem very unusual to an unprepared person at the DT.

Successful, diligent and responsible implementation of these three points, as well as responsible study of the final training tests, will allow you to show an excellent result at the CT, the maximum of what you are capable of.

Found a mistake?

If you think you have found an error in the training materials, please write about it by email (). In the letter, indicate the subject (physics or mathematics), the name or number of the topic or test, the number of the problem, or the place in the text (page) where, in your opinion, there is an error. Also describe what the suspected error is. Your letter will not go unnoticed, the error will either be corrected, or you will be explained why it is not an error.

The session is approaching, and it’s time for us to move from theory to practice. Over the weekend we sat down and thought that many students would benefit from having a collection of basic physics formulas at their fingertips. Dry formulas with explanation: short, concise, nothing superfluous. A very useful thing when solving problems, you know. And during an exam, when exactly what was memorized the day before might “jump out of your head,” such a selection will serve an excellent purpose.

The most problems are usually asked in the three most popular sections of physics. This mechanics, thermodynamics And molecular physics, electricity. Let's take them!

Basic formulas in physics dynamics, kinematics, statics

Let's start with the simplest. The good old favorite straight and uniform movement.

Kinematics formulas:

Of course, let's not forget about motion in a circle, and then we'll move on to dynamics and Newton's laws.

After dynamics, it’s time to consider the conditions of equilibrium of bodies and liquids, i.e. statics and hydrostatics

Now we present the basic formulas on the topic “Work and Energy”. Where would we be without them?

Basic formulas of molecular physics and thermodynamics

Let's finish the mechanics section with formulas for oscillations and waves and move on to molecular physics and thermodynamics.

The efficiency factor, the Gay-Lussac law, the Clapeyron-Mendeleev equation - all these formulas dear to the heart are collected below.

By the way! There is now a discount for all our readers 10% on any type of work.

Basic formulas in physics: electricity

It's time to move on to electricity, even though it is less popular than thermodynamics. Let's start with electrostatics.

And, to the beat of the drum, we end with formulas for Ohm’s law, electromagnetic induction and electromagnetic oscillations.

That's all. Of course, a whole mountain of formulas could be cited, but this is of no use. When there are too many formulas, you can easily get confused and even melt your brain. We hope our cheat sheet of basic physics formulas will help you solve your favorite problems faster and more efficiently. And if you want to clarify something or haven’t found the right formula: ask the experts student service. Our authors keep hundreds of formulas in their heads and crack problems like nuts. Contact us, and soon any task will be up to you.