It is known that the circuit has two fixed value resistors, a switch and a 60V power supply connected by wires. And the power supply voltage is constant. When the switch is in a certain state (open or closed), the electric power of the circuit is 40W. When the switch is in another state, the electric power of the circuit is increased by 20W. The resistance values of the two fixed value resistors are calculated

It is known that the circuit has two fixed value resistors, a switch and a 60V power supply connected by wires. And the power supply voltage is constant. When the switch is in a certain state (open or closed), the electric power of the circuit is 40W. When the switch is in another state, the electric power of the circuit is increased by 20W. The resistance values of the two fixed value resistors are calculated

It is known that the power of the first state circuit is P1 = 40W, and the power of the second state circuit is P2 = 40W + 20W = 60W; from the formula P = u2r, it can be seen that the resistance decreases when the circuit power increases; ① in the series circuit, the total resistance is greater than any partial resistance, the original two resistors are connected in series, the switch is connected in parallel with one of the resistors R2, the switch is closed, and the resistor R2 is short circuited; When the switch is closed, ∵ P = u2r, the resistance value of R1 is R1 = u2p2 = (60V) 260W = 60 Ω; when the switch is disconnected, the total resistance of series circuit is R series = u2p1 = (60V) 240W = 90 Ω; the resistance value of R2 is R2 = R series - R1 = 900 Ω - 60 Ω = 840 Ω; ② in the parallel circuit, the total resistance is less than any sub resistance, the original two resistors are in parallel, the switch controls one resistor R2, when the switch is disconnected, only R1 works Show: when the switch is off, the resistance value of R1 is R1 = u2p1 = (60V) 240W = 90 Ω; when the switch is closed, the power consumed by R2 is P2 ′ = 60w-40w = 20W, and the resistance value of R2 is R2 = u2p2 ′ = (60V) 220W = 180 Ω. Answer: the resistance values of the two resistors are 60 Ω, 840 Ω or 1900 Ω, 180 Ω respectively

In the black box, there are two resistances whose resistance values are both R. the resistance between AB is R and that between BC is 2R. If CD is connected by wire, the resistance between AB is 12R. Please draw the connection diagram of the two resistances in the black box

Resistance relationship of series circuit: the total resistance of series circuit is equal to the sum of the series resistance, and the reciprocal of the total resistance of parallel circuit is equal to the sum of the reciprocal of the parallel resistance. As shown in the figure, there is only one resistance R between AB, and two resistance R between BC are in series. After connecting CD with wire, the two resistance R between ab are in parallel

In a circuit, keeping the voltage constant, the current I (ampere) is inversely proportional to the resistance R (Ohm). When the resistance R = 5 ohm, the current I = 2 ampere. (1) find the functional relationship between I and R; (2) find the value of resistance R when the current I = 0.5 Ampere

(1) Let I = ur ∵ when the resistance R = 5 ohm, the current I = 2 amperes. U = 10. The functional relationship between I and R is I = 10R. (2) when I = 0.5 amperes, 0.5 = 10R, r = 20 (Ohm)

In a circuit with constant voltage, when the circuit is increased by 5 Ω, the current will be reduced to 5 / 6 of the original value, and the original resistance will be?

Let the original resistance R1 = R
Suppose the original current is I1 = 1, R2 = R + 5, then the current I2 = 5 / 6
I1=U/R1=U/R=1
I2=U/R2=U/(R+5)=5/6
Solve the above two formulas
R = 25 Ohm