Find the formula of electric heating

Find the formula of electric heating

1. The general formula for calculating electric energy is: w = uit
2. The general formula for calculating electric heating is: q = I ^ 2rt
3. The formula for calculating the pure resistance of electric energy is: w = uit = I ^ 2rt = (u ^ 2 / R) * t
4. The formula for calculating the pure resistance of electric heating is: q = uit = I ^ 2rt = (u ^ 2 / R) * t
I2R
Q=I²Rt
1
P = UI = I & # 178; r = u & # 178 of R; w = Pt = uit = I & # 178; RT = u & # 178 of R; t r = I1 + I2 (Series) r = (R1 + R2) r = (R1 × R2) (parallel) P = P1 + P2 (relationship between series and parallel electric power, P is total power, P1 and P2 are partial power) I = I1 = I2 = I3 = ··· in (Series) I = I1 + I2 + ··· in (parallel) u = U1 + U2 + U3
1
P = UI = I & # 178; r = u & # 178 of R; w = Pt = uit = I & # 178; RT = u & # 178 of R; t r = I1 + I2 (Series) r = (R1 + R2) r = (R1 × R2) (parallel) P = P1 + P2 (relationship between series and parallel electric power, P is total power, P1 and P2 are partial power) I = I1 = I2 = I3 = ·· in (Series) I = I1 + I2 + ·· in (parallel) u = U1 + U2 + U3 + ·· UN (Series) U = U1 = U2 = U3 = ·· UN Q = I & # 178; RT = w = Pt = uit = R of U & # 178; t (P = I & # 178; RT can be used in any case)
2
Impure resistance: q = u squared divided by R times t
Q = I squared by R multiplied by T
Non pure resistance can be used in electric circuits, such as motors, because most of the motor work in the form of mechanical energy, and the other part is the internal energy generated during work, which is consumed in the form of heat. Therefore, motors are not suitable for Q = uit in pure resistance.
Note: non pure resistance can also be used in pure resistance circuit, see the conditions given in the title. Put it away
Q=I^2*R*t
1: Current
R: Resistance
t: Time
Ampere force and Joule heat
There are two metal guide rails placed in parallel and vertical. A magnetic field is perpendicular to the two guide rails, and the plane of the two guide rails is inward. There is a certain resistance R at the lower end of the guide rails. There is a metal bar with resistance o and good contact with the two guide rails. The contact between the guide rails and the metal bar is released by rest, and all friction and resistance are ignored. Under such conditions, is the Joule heat generated on the resistance equal to the work done by Ampere force?
in other words
Why Joule heat = work done by bil? The topic of today's teacher is very simple, but I don't understand it all the time.
The conductor bar cuts the magnetic induction line, which is equivalent to a power supply to R. according to the conservation of energy, all the electric work of the power supply is used to heat the resistance! That is, the electric work of the power supply is equal to the Joule heat on the resistance
Secondly, the conductor bar is equivalent to the power source, so the non electrostatic force of the power source is the ampere force, so the work done to overcome the ampere force is equal to the electric work of the power source
Remember: in the problem of electromagnetic induction, Ampere force is the bridge between electric energy and other forms of energy, work = energy conversion
For example, if a power supply and a guide rail are placed horizontally, and a metal bar is placed on the guide rail, regardless of all friction, the current flowing through the conductor bar is I, then the ampere force must be B I l. after the conductor bar moves for a certain distance, the electric energy consumed in the circuit is divided into two parts, one is electric heating, the other is electric heating, Part of the energy is converted into the mechanical energy of the conductor rod (only kinetic energy). The value of the mechanical energy is equal to the work done by Ampere force
Not equal to, but also includes the work done by mechanical energy. What is mechanical energy? How can you do work? When the metal rod falls, the potential energy is converted into kinetic energy, which is then converted into the energy of electromagnetic field. Therefore, Joule heat actually comes from the decrease of gravitational potential energy. The gravitational potential energy is transformed into the energy of electromagnetic field in space, and a part of electromagnetic field changes, so Joule heat is produced. It is not clear just now that joule heat is the work of Ampere force. Energy of electromagnetic field? I haven't heard of this term. Can you explain it. ... unfold
Not equal to, but also includes the work done by mechanical energy. What is mechanical energy? How can you do work?
Relationship between total resistivity and resistivity of each part in series and parallel circuits
1. In a series circuit, the total resistance is equal to the sum of the resistances of each part
2. In a parallel circuit, the reciprocal of the total resistance is equal to the sum of the reciprocal of the resistance of each part
3. The resistivity has nothing to do with series and parallel connection
Is the quality of Emma electric car good? What brand is the battery? It's better to drive Emma's
Recently, I want to buy an electric car. I went to Emma's store for a walk and fell in love with one. I haven't made up my mind to come because I'm afraid to buy one with poor quality. Please help me if I know
If you go to Emma Lvyuan Jieante, you can have a good look. You have to go to some stores to buy all kinds of miscellaneous brands. Emma, I feel that they have the best price performance, but the workmanship is not good. Now their new car styles and workmanship are very good. The relatively new one should be Sanqiang, which is very cost-effective and worth buying
1 bulb connected in series with a 4 ohm resistor and connected to a 12 volt power supply can light normally. At this time, the power of the bulb is 8 watts
What is the resistance of the bulb when it is normally illuminated? What is the rated voltage of the bulb?
I worked out two answers for each. The resistance is 8 and 2, and the voltage is 8 and 4
Hand in hand:
Known: P = 8W, u = 12V
Let the resistance of the lamp be r lamp
The total resistance of the circuit is:
R total = 4 + R lamp
According to the conditions, the following equations are established
I = u / 4 + R lamp. 1
I ^ 2R = 8.2
The results are as follows
8R lamp ^ 2-10r Lamp + 16 = 0
The factorization is as follows
(r LAMP-2) (R lamp-8) = 0
Solution: R lamp 1 = 2 (Euro)
R lamp 2 = 8 (Euro)
When R lamp 2 = 2 Ω is substituted into equation 1 or 2, the current is 1 A
Because the voltage drop on the lamp plus the voltage drop on the 4 ohm resistor should be equal to the total voltage of 12V
The voltage drop on the 4 ohm resistor is: U1 = IR = 1x4 = 4V
The voltage drop of R lamp is: U2 = IR lamp = 1x2 = 2V
U1 + U2 = 4 + 2 = 6V, not equal to the total voltage of 12V
Therefore, r = 2 Ω, which does not conform to the reality and cannot be used as the solution of the original equation
Replace the R lamp 1 = 8 ohm into the circuit experience to calculate the actual symbol
The final conclusion is that the resistance of the bulb is equal to 8 ohm
[12/（R+4）]^2*R=8
Finally, r = 8 or 2
After calculating 8 and 2, we need to discuss whether we can burn the bulb. If not, it is correct
I figured out two.
The influence factor of resistance in circuit and its calculation formula
R = ρ L / s, where ρ is the resistivity, l is the length of the material, in M, s is the area, in m ^ 2
The resistivity of some materials increases with the increase of temperature, and vice versa
The resistance value of resistance element is generally related to temperature. The physical quantity to measure the resistance affected by temperature is temperature coefficient a, which is defined as the percentage of resistance value change when the temperature increases by 1 ° C. if the resistance value of any resistance element at temperature T1 is R1, when the temperature rises to T2, the resistance value is R2, R2 = R1 [1 + a (t2-t1)]
The influence factor of resistance in the circuit is environmental temperature, which shows the relationship between resistivity and temperature.
ρ = (1 + (T-20) / 255) * ρ 20 - where ρ 20 is the resistivity at 20 degrees. T is the ambient temperature.
What is the voltage range of electric vehicle 64V controller? Can it connect 72V battery?
What is the low voltage protection of 64V controller?
Hello! The voltage range of the controller is determined according to the use range of the MOS transistor. Generally, the voltage of the 64V battery is about 72V after it is fully charged and stable, and the 72V battery is about 82v after it is fully charged and stable. It can be connected to 72V for operation, but it can not be operated for a long time. Because the controller has undervoltage, the 64V controller will over discharge the battery when it uses 72V battery, At the same time, the high voltage does great harm to the controller. The low voltage protection value of 64V controller is 56V
When a bulb marked "12V 6W" is connected to a 9V circuit, the power consumed by the bulb is__________ If you plug it into a 36 volt circuit and turn it off
When a bulb marked "12V 6W" is connected to a 9V circuit, what is the power consumption of the bulb_______ W. If it is connected to a 36V circuit and can emit light normally, it should be connected in series with a resistance value of 0______ The resistance in Ω
3.375W
48Ω
1 prompt, first calculate the resistance of the bulb
2. Ensure that the current does not exceed the rated current
Bulb resistance:
12 * 12 / 6 = 24 ohm
In 9V circuit
9*9/24=3.375W”
36 / 12 * 24 = 72 ohm
27/8，48
Circuit diagram of measuring wire resistivity with qj19 dual purpose DC bridge
Summary of electrical knowledge
1、 Circuit
The formation of electric current: the directional movement of electric charge forms electric current
Direction of current: from positive to negative
Power supply: a device that provides continuous current (or voltage)
Power is to convert other forms of energy into electrical energy. For example, dry batteries convert chemical energy into electrical energy. Generators convert mechanical energy into electrical energy
Condition of continuous current: power supply and circuit must be closed
Conductor: objects that conduct electricity easily are called conductors, such as metal, human body, earth, saline solution, etc
Glass, insulator, insulator, etc
Circuit composition: by the power supply, wire, switch and electrical components
There are three states of the circuit: (1) path: the circuit connected is called path; (2) open circuit: the circuit disconnected is called open circuit; (3) short circuit: the circuit directly connecting the wire to the two poles of the power supply is called short circuit
Circuit diagram: the diagram of circuit connection indicated by symbol is called circuit diagram
Series connection: connecting the components one by one in sequence is called series connection
Parallel connection: connecting components in parallel is called parallel connection
2、 Current
International unit: Ampere (a); commonly used: Ma, microampere (a), 1 ampere = 103 Ma = 106 microampere
The instrument for measuring current is: ammeter. Its usage rules are: ① ammeter should be connected in series in the circuit; ② current should come in from + terminal and come out from - terminal; ③ the measured current should not exceed the range of ammeter; ④ it is absolutely not allowed to connect the ammeter to the two poles of power supply without using electrical appliances
There are two ranges of ammeters commonly used in laboratory: ① 0-0.6 a, the current value of each cell is 0.02 a; ② 0-3 a, the current value of each cell is 0.1 a
3、 Voltage
Voltage (U): voltage is the cause of current formation in the circuit, and power supply is the device providing voltage
International unit: volt (V); commonly used: kilovolt (kV), millivolt (MV). 1kV = 103v = 106mv
The instrument for measuring voltage is: voltmeter, the rules of use: ① the voltmeter should be connected in parallel in the circuit; ② the current should come in from + terminal and come out from - terminal; ③ the measured voltage should not exceed the range of the voltmeter;
The commonly used voltmeters in laboratory have two ranges: 1) 0-3v, the voltage value indicated by each small grid is 0.1V;
② 0 ~ 15V, the voltage value of each cell is 0.5V
Memorized voltage values: ① voltage of 1 dry battery is 1.5 V; ② voltage of 1 lead-acid battery is 2 V; ③ voltage of home lighting is 220 V; ④ safety voltage is not higher than 36 V; ⑤ industrial voltage is 380 v
4、 Resistance
Resistance (R): refers to the blocking effect of conductor on current. (the greater the blocking effect of conductor on current, the greater the resistance, and the smaller the current passing through the conductor)
Megohm (Ω); commonly used kiloohm (k): 103;
1000 ohm = 103 ohm
The factors that determine the resistance are material, length, cross-sectional area and temperature (R is independent of its u and I)
Sliding rheostat:
Principle: change the length of the resistance wire in the circuit to change the resistance
Function: by changing the resistance in the access circuit to change the current and voltage in the circuit
Name plate: if a sliding rheostat is marked with 50 Ω, the meaning of 2a is: the maximum resistance value is 50 Ω, which is allowed