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All the formulas in the chapter of electric power
(1) series circuit P (electric power) U (voltage) I (current) w (electric work) r (resistance) t (time)
The current is equal everywhere, I1 = I2 = I
The total voltage is equal to the sum of the voltages at both ends of each consumer, u = U1 + U2
The total resistance is equal to the sum of the resistances r = R1 + R2
U1：U2=R1：R2
The total electric work is equal to the sum of the electric work w = W1 + W2
W1：W2=R1：R2=U1：U2
P1：P2=R1：R2=U1：U2
The total power is equal to the sum of the powers, P = P1 + P2
(2) parallel circuit
The total current is equal to the sum of the currents I = I1 + I2
The voltage is equal everywhere U1 = U1 = U
The total resistance is equal to the product of the resistances divided by the sum of the resistances r = r1r2 △ (R1 + R2)
The total electric work is equal to the sum of the electric work w = W1 + W2
I1：I2=R2：R1
W1：W2=I1：I2=R2：R1
P1：P2=R2：R1=I1：I2
The total power is equal to the sum of the powers, P = P1 + P2
(3) electric power of the same electrical appliance
① The ratio of rated power to actual power is equal to the square of rated voltage to actual voltage, PE / PS = (UE / US)
2. Formula of circuit
(1) resistance R
① Resistance is equal to the density of the material multiplied by (length divided by cross-sectional area) r = density × (L △ s)
② Resistance is equal to voltage divided by current R = u △ I
③ The resistance is equal to the square of the voltage divided by the electric power r = UU △ P
(2) electric power W
Electric work is equal to current times voltage times time w = uit (common formula)
Electric work is equal to electric power times time w = Pt
Electric work is equal to charge times voltage w = QT
Electric work is equal to the square of current times resistance times time w = I × IRT (pure resistance circuit)
Electric work is equal to the square of voltage divided by resistance and then multiplied by time w = u &; u △ R × t (same as above)
(3) electric power p
① Electric power is equal to voltage times current, P = UI
② Electric power is equal to the square of current multiplied by resistance P = IIR (pure resistance circuit)
③ The electric power is equal to the square of the voltage divided by the resistance P = UU △ R (as above)
④ Electric power is equal to electric work divided by time p = w: T
(4) electric heating Q
Electric heating is equal to the square of electric current, which is resistance times time q = iirt (common formula)
Electric heating is equal to current times voltage times time q = uit = w (pure resistance circuit)
What is the formula of physical electric power?
Definition formula: P = w / T = uit / T = UI; (W: electric work, t: time)
RELATED INFORMATIONS
- 1. And knowledge points
- 2. Can Ohm's law and Joule's law only be used in pure resistance circuits? Why?
- 3. Electric power: practical problems The resistance of a light bulb L is 10 Ω, which can normally light up under the voltage of 6V. Now connect the light bulb to 9V constant voltage power supply. In order to make the light bulb normally light up, connect a suitable resistance R in the circuit. How do you think to connect the resistance? What is the resistance value of the resistance R? The resistance of a light bulb L is 10 Ω, which can normally light up under the voltage of 6V, Now connect the bulb to 9V constant voltage power supply. In order to make the bulb shine normally, connect a suitable resistance R in the circuit. How do you think to connect the resistance? What is the resistance value of the resistance R?
- 4. According to what parameters of the hydraulic cylinder, what formula can be used to calculate the motor power that drives the piston movement For example, please describe the formula and process in detail,
- 5. The relation and difference between energy and work and force What is their unit and significance
- 6. The relationship between mechanical power and work and energy conversion Since work is a measure of energy conversion, the speed of doing work is also the speed of energy conversion, Why is it true that "the greater the power of a machine, the faster the machine works", Is it wrong to say that the greater the power of the machine, the faster the energy conversion when the machine is working?
- 7. Is the work done by the motor equal to the work done by the friction force on the conveyor belt?
- 8. For junior high school all scientific calculation formula, whether it is chemical or physical, to be complete
- 9. Find the commonly used calculation formula of junior high school science For example, the pressure calculation formula F / s represents the pressure divided by the stress area, which is very common
- 10. The calculation formula of circuit in junior high school
- 11. In the circuit, the power supply voltage is constant. R1 is a certain value resistor, R2 is a sliding rheostat. After the switch S is closed, when the slide rheostat picture P slides before a and B, the maximum indication of voltmeter is 4V. The electric power variation range of resistor R1 is 0.8W ~ 7.2W, then when the slide rheostat picture moves back and forth, the indication range of current scale is? Circuit diagram: the power switch a R1 R2 is connected in series V to measure the voltage of R2
- 12. Xiaoqiang designed an electric kettle, the circuit is as shown in the figure, s is the temperature control switch, R1 is the heater. When the switch S is connected to a, the electric kettle is in the heating state, and the electric power of the heater is 1000W; when the water is boiling, the switch S automatically switches to B, and the electric kettle is in the insulation state, and the electric power of the heater is 160W (1) Please calculate the resistance value of R1 and R2 (regardless of the influence of temperature on the resistance value) (2) in order to make full use of electric energy, on the premise of not changing the circuit connection method, please put forward reasonable improvement methods for the design of Xiaoqiang
- 13. Physics problem about electric power 220V 100W In 110 V circuit Find r =? P=? Heat generated in 1min? Please write down the detailed process (formula used) Please, we have to write the process
- 14. What time units, seconds and hours are used to calculate electric power
- 15. In the same time, the greater the current in the appliance, the more work the current does? Is that right? Why not
- 16. The following statement about electric power is correct () A. Electric power is a physical quantity indicating how much work is done by current. B. The more electric energy consumed by electrical appliances in the same time, the greater the electric power. C. when several bulbs in series work, the electric power of bulbs with large resistance is smaller. D. the more work done by current, the greater the electric power
- 17. The more work the current does per unit time, the greater the electric power, right?
- 18. How to calculate the electricity consumption per hour?
- 19. The electric energy meter can be used to measure the hourly electricity consumption of electrical appliances. Xiao Li wants to know the hourly electricity consumption of the hair dryer used by his hairdresser. He only knows that his rated voltage is 220 V, and there is no other data. Please use the general household electric energy meter [the data on the nameplate is as follows: 220 V 1325 kW · h 2.5 (5) a 50 Hz A simple method is designed to help Xiao Li calculate the hourly power consumption of this hair dryer Fast, fast, good answers plus points
- 20. The electric energy meter is marked with 3000r / kW · h. The primary electric appliance works alone, and the dial turns 150 turns in 10 minutes to calculate the electric power of the electric appliance