Try to write the differential form of Maxwell equations and auxiliary equations, and explain the relationship between time-varying electromagnetic field and electrostatic field, constant electric field and constant magnetic field

Electrostatic field, constant electric field and constant magnetic field are all special forms of time-varying electromagnetic field. Among them, electrostatic field only has charge ρ, the derivative of B with respect to time is 0, and the closed line integral of electric field intensity is equal to 0; constant electric field is similar to electrostatic field

What is the physical meaning of integral form and differential form of Faraday's law of electromagnetic induction?
Integral form, differential form and physical meaning of Faraday's law of electromagnetic induction?

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What is the physical meaning of PID differential coefficient

The derivative term slows the rate of change of the controller output and this effect is most noticeable close to the controller setpoint.Hence ,derivative control is used to reduce the magnitude of the overshoot produced by the integral component and improve the combined controller-process stability.However ,differentiation of a signal amplifies noise and thus this term in the controller is highly sensitive to noise in the error term,and can cause a process to become unstable if the noise and the derivative gain are sufficiently large.

A car from city a to city B was originally planned to arrive in 5 hours. If the speed is increased by 25%, how many hours ahead of time?
A truck goes back and forth between city a and city B. the average speed from city a to city B is 90 km, and the average speed from city B to city a is 60 km?

If the speed becomes 1.25 times, then the time becomes 5 / 1.25 = 4 hours
Let the distance be 1, then 1 / 90 + 1 / 60 = 2 / V, v = 70 km / h

As shown in the figure, it is known that ∠ B = ∠ C = 90 °, M is the midpoint of BC, DM bisects ∠ ADC

(1) Prove that: through the point m, make me ⊥ ad, perpendicular foot is e, ∵ DM ⊥ ADC, ∵ 1 = ∠ 2, ∵ MC ⊥ CD, me ⊥ ad, ∵ me = MC (the distance from the point on the bisector to both sides of the angle is equal), and ∵ MC = MB, ∵ me = MB, ∵ MB ⊥ AB, me ⊥ ad, ∵ am ⊥ DAB (the distance from the two sides of the angle is equal); (2) DM ⊥ am They are: ∵ B = ∵ C = 90 °, ∵ DC ⊥ CB, ab ⊥ CB, ∵ CD ∥ AB (two lines perpendicular to the same line are parallel), ∵ CDA + ∵ DAB = 180 ° (two lines are parallel, and the inner angles of the same side are complementary), and ∵ 1 = 12 ⊥ CDA, ∵ 3 = 12 ⊥ DAB (angular bisector definition) ∵ 2 ∵ 1 + 2 ∥ 3 = 180 °, ∵ 1 + 3 = 90 ° and ∵ amd = 90 degrees, that is DM ⊥ am

As a small fishing village in the early 1960s, South Korea's Auto City Yushan city is similar to every special economic zone in China

Shenzhen is also a small fishing village before the reform and opening up

When x is a real number, the value of the algebraic formula √ (16-x) & sup2; + √ (X-13) & sup2; is a constant, which is () a.29 B.16 c.13

When 13 ≤ x ≤ 16
√（16-x）²+√（x-13）²
=16-x+x-13
=3

The length of an express train is 70m, and that of an idle train is 80m. If two trains go in the same direction, it takes 20s for the express train to overtake the idle train completely; if two trains go in the same direction
If the two cars meet each other and leave completely, the time is 4S. How many meters per second can the two cars walk
The process and thinking of solving questions

Speed sum (70 + 80) △ 4 = 150 △ 4 = 37.5
Speed difference (70 + 80) △ 20 = 150 △ 20 = 7.5
Express speed (37.5 + 7.5) △ 2 = 45 △ 2 = 22.5 M / S
Slow speed 22.5-7.5 = 15 m / S

It is known that the focus of the hyperbola is on the y-axis, the center is at the origin, and the point P1 (3, - 4 radical 2) P2 (9 / 4,5). On this hyperbola, find the standard square of the hyperbola

As shown in the figure:

A truck team transported a batch of cement from the factory to the construction site. On the first day, it transported 14 and 7 tons of all cement, and on the second day, it transported the remaining 25 and 2 tons. In this way, 518 tons of all cement remained. How many tons of cement were there?

Suppose the total weight of cement is x tons, then 14x + 7 tons are transported on the first day, and (x-14x-7) × 25 + 2 tons are transported on the second day, then: (14x + 7) + [(x-14x-7) × 25 + 2] = (1-518) x, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 1

Try to write the differential form of Maxwell equations and auxiliary equations, and explain the relationship between time-varying electromagnetic field and electrostatic field, constant electric field and constant magnetic field