If the indication of the ammeter increases by 4 times, R? Ohm resistance should be given Such as the title Better have an explanation

If the indication of the ammeter increases by 4 times, R? Ohm resistance should be given Such as the title Better have an explanation

Parallel resistance is set as X
1/R+1/X=4/R
X=R/3
Three resistors with the same resistance value are paralleled on the original resistance
In the circuit shown in Figure 6, the resistance R2 = 6, after the switch S is closed, the indication of ammeter A1 is 1.5A, and the resistance R1 is eliminated
In the circuit shown in Figure 6, the resistance R2 = 6, after the switch S is closed, the indication of ammeter A1 is 1.5A, the electric power consumed by resistance R1 is 3W, and the power consumed in the circuit is less than 9W
The resistance value of R1? A2?
No, it's r1r2 parallel, A1 trunk, a2r1 branch
Just a switch, on the main road
Because the power consumed in the circuit is less than 9W, ptotal = P1 + P2
Where is the switch S?
Circuit diagram
As shown in the figure, R1 = 30 Ω, R2 = 80 Ω, the power supply voltage remains unchanged, assuming that the filament resistance remains unchanged. (1) when k, K1 and K2 are closed, the indication of ammeter A1 is 0.4A, and the small bulb l just lights normally. What are the power supply voltage, the rated voltage of small bulb and the indication of A2? (2) When k is closed and K1 and K2 are open, the indication of ammeter A2 is 0.1A. What is the actual power of the small bulb? (3) What is the power rating of the small bulb?
(1) When k, K1 and K2 are closed, the equivalent circuit diagram is as follows: ∵ R2 and ammeter are short circuited, the number of A2 is 0; ∵ the voltage at both ends of each branch of parallel circuit is equal, ∵ u = UL = U1 = i1r1 = 30 Ω× 0.4A = 12V. (2) when k is closed, K1 and K2 are open, the equivalent circuit diagram is as follows: voltage at both ends of bulb L, UL ′ = u-u2 = u-i2r2 = 12v-0.1a × 80 Ω = 4V, ∵ actual voltage of bulb Power pl ′ = UL ′ I2 = 4V × 0.1A = 0.4W. (3) resistance RL = u ′ Li2 = 4v0.1a = 40 Ω, rated power pl = u2lr2 = (12V) 240 Ω = 3.6W. Answer: (1) when k, K1 and K2 are closed, the power supply voltage is 12V, the rated voltage of small bulb is 12V, A2 indication is 0; (2) when k is closed, K1 and K2 are disconnected, the actual power of small bulb is 0.4W; (3) the rated power of small bulb is 3.6W
How to calculate the total power of physical circuit
The total power is obtained by multiplying the voltage by the total current. When you connect two "220 V 100 W" bulbs in series into the 220 V circuit, the total power consumed by the two lamps is 50 W. because the total current decreases after the series connection, the total current increases after the parallel connection
Additional questions: there is a relationship between the resistance R and power P of an electrical appliance and the voltage at both ends of the appliance, P = u2r. There are two electrical appliances with the same appearance, the resistance of a is 18.4 Ω, and the resistance of B is 20.8 Ω?
Let the side length of the square be x cm. According to the meaning of the title, X2 = π· 12  x = π cm. From the meaning of the title, 43 π rr3 = 9850r ≈ 13.3 ∵ P = u2r ∵ u = 1500r. When r = 18.4, u ≈ 166.1. When r = 20.8, u ≈ 176.6 ∵ 166.1 ＜ 170 ∵ use the first electric appliance
What is the unit of milliampere left in ohm?
Ohm * ma * 10 ^ (- 3) = v
What is the definition of Joule?
1 joule =?
Joule is the unit of work and energy (F: force, N, s, distance, m, m, mass, kg, a, acceleration, M / S ^ 2)
Merit:
W = FS = MAS, 1 joule = 1 N · M = 1 kg · m2 / second power
Electric work
W = Pt, 1 joule = 1 W · s
quantity of heat:
Q = I ^ 2rt, 1 joule = 1 second power ampere · ohm · sec
The Joule unit is in memory of physicist James Joule
How to calculate current with known voltage and power
According to the formula P = u * I, I = P / u; the result can be obtained by calculation. Of course, for power transmission lines, power refers to the power loss on the transmission line, not the transmission power
When the voltage at both ends of the white flag lamp decreases, the current passing through it decreases___ (increase or decrease) the power of the consumer____ (increase or decrease)
Please write down the formula and explain how to judge it?
When the voltage at both ends of the incandescent lamp decreases, the current through the bulb I = u / R without considering the change of filament resistance, so I decreases with the decrease of voltage U;
If the power P = IU, I and u decrease, the power P decreases
All decrease u = IR P = I ^ 2R
When the voltage at both ends of the white flag lamp decreases, the current through it decreases___ At this time, the power of the consumer decreases____ (increase or decrease)
Ohm's law
P = UI, and the change of bulb resistance with temperature is basically ignored
What milliohm is one ohm
One ohm is 1000 milliohm