The relationship between current, resistance, power and voltage

The relationship between current, resistance, power and voltage

Power P = UI=
IR=U/R=W/T
Work w = uit = IRT = ut / R
U = IR, P = UI, P = IIR = UU / R
The relationship between resistance and current, voltage, electric power and electric power
Ohm's Law: I = u / R note: the deformation of Ohm's Law: r = u / I is only the formula for calculating resistance, that is, the formula for calculating resistance. The definition of resistance is r = ρ L / S (ρ is the resistivity, l is the length of the conductor, s is the cross-sectional area of the conductor). The formula for calculating electric power is p = UI, which is the principle formula for calculating electric power. It is applicable to any circuit
Electric work (W) = current (I) × voltage (U).
Electric power (P) = w △ t (the electric energy consumed by an electric appliance in one second).
Resistance = voltage / current, electric power = voltage * current, electric power = electric power * time
How many W power supply should a 100W electrical appliance be equipped with? How much higher is the maximum power of the general power supply than the actual power of the load?
Generally, 1.2-1.5 times is about 150W
Small power supply can be smaller, if the kilowatt level is another matter
Why does the resistivity of metals increase with the increase of temperature
Metal conduction is caused by the directional movement of free electrons in the metal. In addition to free electrons, atoms in the metal also vibrate near their positions. The intensity of this vibration is related to the temperature of the metal. The higher the temperature is, the more intense the vibration is. At the same time, the greater the chance of collision between free electrons and such atoms is, the more the directional movement of electrons is hindered, that is, the resistance increases
At present, there is a "220 V & nbsp; 100 W" electric bulb. If it is connected to the home circuit, the current passing through the bulb is 0______ A. If it is connected to a circuit with a voltage of "110V", the resistance of the bulb is______ Ω (regardless of the effect of temperature on the resistance), the actual power is______ W．
(1) The rated current of the bulb: Il = plul = 100w220 v = 511A ≈ 0.45 a, the resistance of the bulb: RL = ulil = 220 V 511A = 484 Ω, when it is connected to the home circuit, the bulb lights normally, so the current passing through the bulb is 0.45 a; (2) when the influence of temperature on the resistance is not considered, the resistance of the bulb and both ends
Can 120V AC power supply be used in China
No, it can only be reduced by transformer
It doesn't work if the voltage is not enough
Because the power supply in China is 220 v
Suppose the resistance of the circuit is r, connected to 220 V, power = 220 & # / R Over rated power
Output power: 178? / 120 V This is the rated power
So the appliance is damaged
Is metal resistivity proportional to temperature
I'm glad to answer for you. After in-depth study, the relationship between resistivity and temperature is not proportional, but a linear function. There is a formula. The law of material resistivity ρ changing with temperature is ρ = ρ 0 (1 + at), where α is called resistance temperature coefficient, ρ 0 is the temperature range of material resistivity at t-0 ℃, α is
Two identical lamps are connected in the 220 V voltage of the home circuit, and the total power is 40 W,
If two lamps are connected in series in a 220 V voltage circuit, what is the power consumption of each lamp?
P1=U^2/(R/2)
40=220^2/(R/2)
Total power of two lamps in series: P2 = u ^ 2 / (R + R) = 10 (W)
So the power consumption of each lamp is 5W (10W / 2 = 5W)
P1 = u ^ 2 / (1 / 2R) = 40W; so P2 = u ^ 2 / (2R) = 10W, that is 5W for each lamp
As shown in the figure, the regulated power supply is connected between M and N. when a and B are disconnected, UAB = 120V, and when a and B are connected with a "220V & nbsp; & nbsp; 100W" bulb, UAB = 110V. At this time, the power input of M and N is () a.25wb. 27.27wc. 102.27wd. 2.27w
When a and B are off intermittently, UAB = 120V, the power supply voltage is u = UAB = 120V; according to P = UI = u2r of "220V & nbsp; & nbsp; 100W" bulb, the resistance of filament RL = U2, P = (220V) 2100W = 484 Ω, when a and B are connected with "220V & nbsp; & nbsp; 100W" bulb, UAB = 110V, the power supply voltage is
In the experiment of measuring the resistivity of metal, because the resistance of the measured metal wire is small, so what kind of connection method must the ammeter use in the experimental circuit, internal connection method or external connection method
Small resistance, external connection method