Seek physics and electricity group, voltage, current, electric power related knowledge point induction It mainly refers to the application of knowledge points and formulas related to electric group, voltage, current and electric power, such as when to use what formula, etc

Seek physics and electricity group, voltage, current, electric power related knowledge point induction It mainly refers to the application of knowledge points and formulas related to electric group, voltage, current and electric power, such as when to use what formula, etc

(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 equals current times voltage times time q = uit = w (pure resistance circuit)

When a small lamp works normally, the resistance is 10 Ω, and the voltage of the normal working room is 4 v. if we want to make the small lamp work normally, we only have the voltage of 10 Ω
The resistance of a small electric lamp is 10 Ω when it works normally, and the voltage of the normal working room is 4 v. if we want to make the small electric lamp work normally, but we only have a power supply with a voltage of 6V, what should we do? Try to answer through calculation
Physics problems in grade three Get rid of the answer

Two such small lamps are connected in parallel, and then connected in series with a small lamp. According to Ohm's resistance law, it can be found that the small lamp in parallel is 2V, the small lamp in series is 4V, and the small lamp in series can light normally!