The physical layer is the foundation of all networks. How many volts are used to represent 1, how many volts are used to represent 0, and how long does a bit last for microseconds?

The physical layer is the foundation of all networks. How many volts are used to represent 1, how many volts are used to represent 0, and how long does a bit last for microseconds?

For example, the electrical characteristics of RS-485: Logic "1" is expressed by the voltage difference between two wires as + (2-6) V; logic "0" is expressed by the voltage difference between two wires as - (2-6) v
The general expressions of quadratic functions are --, vertex and zero————
General form
Y = ax ^ 2 + BX + C (a ≠ 0, a, B, C are constants), vertex coordinates are [- B / 2a, (4ac-b ^ 2) / 4A]
The values of a, B and C can be solved by substituting three points into the equation to get a system of linear equations of three variables
Vertex type
Y = a (x + H) ^ 2 + K (a ≠ 0, a, h, K are constants), vertex coordinates (- H, K), axis of symmetry x = - H,
Intersection type
Y = a (x-x &;) (x-x &;) (a ≠ 0) [only for the parabola with intersection a (X &;, 0) and B (X &;, 0) with X axis, i.e. y = 0, i.e. B ^ 2-4ac ≥ 0]
The properties of quadratic function
General formula: y = ax & # 178; + BX + C
Vertex formula: y = a (X-H) ² + K;
Zero form: y = a (x-x1) (x-x2)
y=ax^2+bx+c
y=(x+b/2a)^2+(4ac-b^2)/4a
y=a(x-x1)(x-x2)
General formula: y = ax & # 178; + BX + C
Vertex formula: y = a (X-H) ² + K;
Zero form: y = a (x-x1) (x-x2)
General formula: y = ax ^ 2 + BX + C
Vertex formula: y = a (x + 2A / b) ^ 2 + 4a (4ac + B ^ 2)
Zero form: y = a (x + b) (x + C)
General formula: y = ax & # 178; + BX + C (a ≠ 0, a B C is constant) vertex formula: y = a (x + H) &# 178; + K intersection formula: (with X axis) y = a (x-x1) (x-x2)
What is the relationship between zeros and poles of complex functions?
There is a problem. It says that 0 is the third-order zero of the denominator, not the zero of the molecule, so 0 is the third-order pole of the function. Why do you say that? If 0 is the third-order zero of the denominator, and it is the first-order zero of the molecule, then how many Poles of the function is 0? What is the relationship between the zero and the pole
When 0 is the third order zero of denominator, not the zero of molecule, 0 is the third order pole of function. This is the definition of pole
When 0 is the third-order zero of denominator and the first-order zero of molecule, then 0 is the second-order pole of function. This is obtained by combining the definition of pole and de homogeneous point
What's the relationship between zero point and pole? You can see it in the book of complex variable function. You can know which book you are using
Transfer function of zero pole frequency response
Briefly explain their respective influences on the system, such as the pole affects the stability of the system, the system on the left side of the coordinate is stable, and the system on the right side is unstable. What does the zero affect? How does it affect? And how does the frequency response describe the relationship between the input and output of the system?
I get a transfer function of the system
pole(G2) zero(G2)
ans = ans =
0 -2.5655
-2.5946 2.5277
two point five five five five
-0.0190
The Bode diagram is also drawn,
1. The pole affects the stability of the system. When the system is stable, it also affects the motion mode of the system. For example, the response contains e ^ (- t) ah, t * e ^ (- t) ah. 2. The zero point does not affect the stability and mode, but for the specific input signal, it affects the proportion of each mode in the response
I have an electric meter. There are three current transformers on the meter. The current transformer is 100 / 5. I want to know how many times it is
20 times, 100 / 5 = 20
Mathematical function resistance voltage power ohm
Xiaohuashang electric appliance store bought a table lamp. He saw that the resistance on it was adjustable, and the range was
484-1210 ohm, known voltage is 220 v
(1) Write out the relationship between output power P and resistance R
(2) What is the power range of this lamp?
Thank you in advance~~~
I'm really in a hurry to be quick!!!!!!!!!!!!!!!!!!!!!!!
I have to hand in my homework tomorrow~~~~~
(1)P=UI=U^2/R
(2) Bring in R, U
P:40w-100w
First positive solution
(1)P=U²/R
(2)40W--100W
Definitely right! I'm a physics teacher!
A furnace connected to the 220 V power supply works normally, the resistance of the furnace is 48.4 ohm
1 current through wire
2. Work done by the current for 10 minutes
3 rated power of electric furnace
This furnace is connected to the circuit of 220 V, the actual power consumption is very low
(1)I=U/R=5A
(2)W=UIt=220*5*10*60=6.6×10^5j
(3)P=UI=220*5=1100W
(4) This electric furnace is connected to the circuit of 220 V, the actual power consumption is the rated power = 1100 W
1. I = u / r = 220 V / 48.4 Ω = 4.54a
2.W=Pt=U^2t/R=6*10^5J
3. Because the electric furnace is connected to the 220 V power supply and works normally, that is, the rated voltage is 220 V, so the rated power P = u ^ 2 / r = 1000 W
4. Because the voltage has not changed, the actual power is still 1000W (it may not be connected to 220V)
Connect two "220 V, 40 W" and "220 V, 100 W" incandescent lamps in series on the 220 V circuit. If the resistance of the filament does not change with the temperature, try to find: (1) the ratio of the actual power consumed by the two bulbs; (2) the maximum total voltage allowed to be added when the two lamps are connected in series on the premise of not exceeding the rated power
(1) According to P = u2r, the resistance of "220 V, 40 W" bulb R1 = 220, 240 Ω = 1210 Ω, the resistance of "220 V, 100 W" bulb R2 = 220, 2100 Ω = 484 Ω, so when two bulbs are connected in series and the current of series circuit is equal, the ratio of power consumed by two bulbs is p1p2 = i2r1, i2r2 = r1r2 = 12
How many current transformers and meters are used for 70 square cable
70 square meters depends on whether you are copper core or aluminum core. The safe current carrying capacity of copper core is 210a
The safe current carrying capacity of aluminum core is 175A
All meters equipped with mutual inductors choose 1.5 (6) A. as for how big your mutual inductor is, it depends on your load current. It's better to be larger than and close to your actual load. For example, if your actual load is 100A, then you choose 150g5
The relationship between resistance R, power P and voltage U of a household appliance is p = R / u squared
(1) If the power of a consumer is 200 watts and the resistance is 210.5 ohm, what is the maximum voltage that the consumer can withstand?
(2) If the two ends of the appliance are connected with 220 V lighting voltage, will the appliance burn out?
P = u ^ 2 / R & nbsp; indicates that it is a pure resistance circuit, u ^ 2 = RP & nbsp; & nbsp; u = √ RP & nbsp; = 205.18v, the maximum voltage is 205.18v & nbsp; less than 220V & nbsp; so the appliance will burn out
(1) there is p = u & # 178; △ R
u=√﹙pR﹚=205.18v
⑵205.18＜220
The electrical appliances will burn out
According to P = u ^ 2 / R;
u^2=p*R
u=205
1、U=(PR)^0.5=205V
2. If the two ends of the appliance are connected with 220 V lighting voltage, the appliance will not burn out, because with the increase of temperature, the resistance will increase and the actual power will be reduced.