What is the function of rotor winding in motor? Do all motors need rotor winding? Is rotor winding electrified by brush? Is it usually stator winding or rotor winding?

What is the function of rotor winding in motor? Do all motors need rotor winding? Is rotor winding electrified by brush? Is it usually stator winding or rotor winding?

The working principle of the motor is simply that the interaction between the stator magnetic field and the rotor magnetic field. The stator winding can produce the magnetic field. If the rotor has no winding, how can it produce the magnetic field? Then where can the interaction between the magnetic field and the magnetic field come from? Therefore, the stator and the rotor must have windings. It is certain that the common motor stator has windings

1. The north and south poles of the electromagnet are related to and. 2. The small motor consists of, and three parts. There are a group of coils on the rotor of the small motor. The commutator is installed on the rotor
On the other hand, it is used to connect the current and connect the circuit
3. Although there are three forms in nature
There are many kinds of energy around us, such as,, and so on
5. In the electric toy car, drive the car forward

1. Winding method of current direction coil 3. Solid liquid gas 4. Object moving, heating and luminous being lifted up 5. Power generated by motor

Working principle of generator and motor
The generator is electromagnetic induction
Motor is also a few words
What other high school instruments use these two working principles!

The principle of the motor is: the electrified coil is forced to rotate in the magnetic field
It can also be said that an electrified conductor is forced to move in a magnetic field
Transformer is the use of the principle of electromagnetic induction
Voltmeter, ammeter and electric energy meter are all made of the principle that the electrified coil is forced to rotate in the magnetic field

There is a rectangular grassland in the campus. Its perimeter is 96 meters, and its length is three times of its width. How many square meters is the area of this grassland? Use the equation

If the width is x meters, the length is 3x meters
x+3x=96/2
4x=48
x=12
3x = 36m
Area: 12 * 36 = 432 square meters

In the parallelogram ABCD, O is the intersection of diagonals, and Ba vector and BC vector are used to represent Bo vector

Make a graph first, and then know that AE is parallel to CF
So the angle EAO = OCF
Because EF is perpendicular to AC, the angle EOA = COF = 90 degrees
And because o is the midpoint of AC, so Ao = Co
So the triangle AEO is equal to the triangle COF
So AE = CF EO = fo
Because EO = fo Ao = co angle EOC = AOF
So the triangle eco is equal to the triangle AOF
So EC = AF angle eco = oaf angle
So EC is parallel to AD
So quadrilateral aecf is parallelogram
Because EO = fo co = co angle EOC = angle foc
So the EOC of triangle is equal to the COF of triangle
So EC = CF
So EC = CF = AE = AF
Because quadrilateral aecf is parallelogram
So the quadrilateral aecf is diamond

The factorization of x3-3x2 + 4,

Building owner,
The original formula = (X & # 179; - 2x & # 178;) - (X & # 178; - 2x) - (2X-4)
=（x-2）（x²-x-2）
=（x-2）（x-2）（x+1）
=（x+1）（x-2）²

How to prove that 2 ^ (n + 2) * 3 ^ n + 5n-4 can be divisible by 25

2^（n+2）*3^n+5n-4
=4*2^n*3^n+5n-4
=4*6^n+5n-4
=4（6^n-1）+5n
The bit of 6 ^ n-1 must be 5
When n = 4k-3, the last two digits of 4 (6 ^ n-1) + 5N are 25, which can be divided by 25;
When n = 4k-2, the last two digits of 4 (6 ^ n-1) + 5N are 50, which can be divided by 25;
When n = 4k-1, the last two digits of 4 (6 ^ n-1) + 5N are 75, which can be divided by 25;
When n = 4K, the last two digits of 4 (6 ^ n-1) + 5N are 00, which can be divided by 25;
Therefore, 2 ^ (n + 2) * 3 ^ n + 5n-4 must be divisible by 25

The two focal points F1, F2 and P of the ellipse x ^ 2 / A ^ 2 + y ^ 2 / b ^ 2 = 1 (a, b > 0) are on the ellipse C, and Pf1 ⊥ F1F2, | Pf1 | = 4 / 3, | PF2 | = 14 / 3. (1) find the ellipse
The two focal points F1, F2 and point P of ellipse x ^ 2 / A ^ 2 + y ^ 2 / b ^ 2 = 1 (a, b > 0) are on ellipse C, and Pf1 ⊥ F1F2, | Pf1 | = 4 / 3, | PF2 | = 14 / 3. (1) the equation of ellipse C is solved. (2) when a > b > 0, if the line L passes through the circle x ^ 2 + y ^ 2 + 4x-2y = 0, the center m of circle teaches the ellipse to a and B, and a and B are symmetric with respect to point m, the equation of line L is solved

Tips:
one
|PF1|=4/3,|PF2|=14/3 2a=|PF1|+|PF2|=6 a=3 a^2=9
PF1⊥PF2 |PF1|^2+|PF2|^2==|F1F2|^2=212/9=(4c)^2 c^2=53/9
The equation of B ^ 2 = a ^ 2-C ^ 2 = 28 / 9 ellipse C: x ^ 2 / 9 + 9y ^ 2 / 28 = 1
two
If the line L passes through the center m of the circle x ^ 2 + y ^ 2 + 4x-2y = 0, the intersection ellipse C: x ^ 2 / 9 + y ^ 2 / 4 = 1 lies at two points a and B, and a and B are symmetric with respect to point m, the equation of the line L is obtained
Let the slope of the line be K,
Write the linear equation according to m and K and substitute it into the ellipse C: x ^ 2 / 9 + y ^ 2 / 4 = 1 to get X1 + x2 = Y1 + Y2=
At the same time, X1 + x2 = 2 times the abscissa of M, Y1 + y2 = 2 times the ordinate of M
Find K

The product of the three primes is 42. The three primes are______ 、______ 、______ ．

42 = 2 × 3 × 7, so the product of the multiplication of the three prime numbers is 42, and the three prime numbers are 2, 3 and 7 respectively

A + 2B + AB = 30 to find the minimum value of 1 / AB
Hurry, hurry, hurry

There should be conditions: a > 0, b > 0?
Let 2Ab = 2T under the root sign
Then AB = 2T * t
30=a＋2b+ab＝a＋2b＋2t*t＞＝4t＋2t*t
t*t＋2t－15＜＝0
（t＋5）（t－3）＜＝0
T > 0, t + 5 > 0
So T-3 ＜ = 0, t ＜ = 3
ab＝2t*t