A summary of physical knowledge in this book
The concept of names in this book
Name meaning symbol unit (universal unit) unit symbol
The magnitude of current intensity in current loop I Ampere (mA) A(mA)
Causes of current generation in voltage circuit U volts (kilovolts, millivolts) V (kilovolts, millivolts)
Resistance conductor's obstruction to current R ohm (kiloohm, megaohm) (k, m)
The speed at which electric power and current do work P Watts (kW, horsepower) W (kW, horsepower)
Energy W Joule (kWh) J (kWh) of work done by electric energy flow.
Wave speed The propagation speed of electromagnetic waves is c meters per second (kilometers per second) and m/s (kilometers per second).
The length of a wavelength of electromagnetic wave is m (km) m (km).
The number of wavelengths with the frequency of 1 sec f Hz (kilohertz, megahertz) Hz (kilohertz, megahertz).
Related formulas in this volume
Name formula meaning deformation formula
Ohm's Law I = U/R Current is proportional to voltage and inversely proportional to resistance U = I RR = U/I.
Electric power formula1p = w/tElectric power is directly proportional to electric energy and inversely proportional to time (both should be considered at the same time) w = p TT = w/p.
Electric power formula 2 P = I U Electric power is equal to the product of current and voltage I = P/UU = P/I.
Electric power formula 3 P = I2 R Electric power is equal to the product of the square of current and resistance R = P/I2.
Electric power formula 4 P = U2/R Electric power is directly proportional to the square of voltage and inversely proportional to the resistance r = U2/p..
Electromagnetic wave velocity formula c = f product of wave velocity and wavelength and frequency = c/ff = c/
This book is about scientists.
Names and nationality stories involve physical knowledge.
Omid 1826 summarizes the relationship between physical quantities of ohm's law circuit.
Oster Denmark discovered the relationship between electricity and magnetism and the magnetic effect of current in 1820.
183 1 year, Faraday discovered the regular electromagnetic induction phenomenon of current generated by magnetic field in Britain.
Bell America invented the transmission of telephone information in 1876.
Franklin invented lightning rod in America to use electricity safely.
Shen Kuo and China discovered in the Song Dynasty that the geographical poles and geomagnetic poles did not completely coincide with the geomagnetic field.
1960 maiman invented the first ruby laser.
Morse invented telegraph digital communication.
Total score relationship of current, voltage and resistance in series-parallel circuit
Expression of total score relation of current, voltage and resistance under connection condition
The currents in series circuits are equal everywhere. Itotal = I 1 = I2。
The total voltage is equal to the sum of the voltages of all appliances. Utotal = U 1+U2。
The total resistance is equal to the sum of the resistances of all electrical appliances, and R total = R 1+R2.
The total current of the parallel circuit is equal to the sum of the currents of each branch. Itotal = I 1+I2。
The voltage is equal everywhere. U total = U 1 = U2.
The sum of the reciprocal of total resistance is equal to the sum of the reciprocal of each branch.
I ohm's law
1.i = u/r (ohm's law: the current in a conductor is directly proportional to the voltage across the conductor and inversely proportional to the resistance of the conductor).
2.I = i 1 = I2 = … = In (characteristics of current in series circuit: current is equal everywhere).
3.U = U 1+U2+…+UN (characteristics of voltage in series circuit: in series circuit, the total voltage is equal to the sum of voltages at both ends of each part of the circuit).
4.I = i 1+I2+…+In (characteristics of current in parallel circuit: the current on the main line is equal to the sum of currents in each branch).
5.U = U 1 = U2 = … = UN (characteristics of voltage in parallel circuit: the voltages at both ends of each branch are equal. Equal to the supply voltage)
6.R = r 1+R2+…+RN (characteristics of resistors in series circuit: total resistance is equal to the sum of the resistances of all parts)
7.1/r =1/r1+1R2+…+1/rn (characteristics of resistors in parallel circuits: the reciprocal of the total resistance is equal to the sum of the reciprocal of all parallel resistances).
8.R and = R/n(n (formula for calculating total resistance when n identical resistors are connected in parallel)
9.R series = NR (formula for calculating total resistance when n identical resistors are connected in series)
10.u1:U2 = r1:R2 (the relationship between voltage and resistance in series circuit: the ratio of voltage is equal to the ratio of their corresponding resistances).
11.i1:i2 = r2: r1(the relationship between current and resistance in parallel circuit: the ratio of current is equal to the inverse ratio of their corresponding resistances).
Second, the power part
12.p = UI (empirical, applicable to any circuit)
13.p = w/t (definition, applicable to any circuit)
14.Q = I2RT (Joule's law, applicable to any circuit)
15.P = P 1+P2+…+PN (applicable to any circuit)
16.W = UIT (empirical value, applicable to any circuit)
17.P=I2R (compound formula, only applicable to pure resistance circuits)
18.P=U2/R (compound formula, only applicable to pure resistance circuits)
19.W=Q (empirical formula, only applicable to pure resistance circuits. Where w is the work done by the current flowing through the conductor and q is the heat generated by the current flowing through the conductor)
20.W=I2Rt (compound formula, only applicable to pure resistance circuit)
2 1.W=U2t/R (compound formula, only applicable to pure resistance circuits)
22. p1:p2 = u1:U2 = r1:R2 (the relationship between electric power and voltage and resistance in series circuit: in series circuit, the ratio of electric power is equal to the ratio of their corresponding voltage and resistance).
23. p1:p2 = I1:I2 = R2: r1(the relationship between electric power and current and resistance in parallel circuit: in parallel circuit, the ratio of electric power is equal to the ratio of their corresponding current and the inverse ratio of their corresponding resistance).