Electricianism Problem solving please note that it is six sub questions, please title number. ）

1. Mutual exclusivity; Mutual attraction.

2. Potential difference (junior high school does not learn the definition of voltage, nor does it test).

3Because there is a difference in electric potential, it is like water flowing downward.

4 is determined by the substance.

The resistance of a conductor at isothermal temperatures, which is proportional to its length, inversely proportional to its cross-sectional area, and is related to the substances that make up the conductor.

Resistivity of a substance = resistance of a conductor of this substance per unit length and cross-sectional area at 20 degrees Celsius.

RS L in Euro * Meter.

5. The relationship between the current passing through the resistor and the voltage at both ends of the resistor.

6. Middle schools do not learn this knowledge.

1. Repel each other and attract.

2. Electric potential difference.

3. There is a potential difference.

4. Voltage divided by current.

5. Ohm's law refers to the fact that under constant conditions, the current intensity through a conductor is proportional to the voltage at both ends of the conductor, that is, i u, or written as i = u r, and the r in the formula is called the resistance of the conductor Ohm also summarized two experimental laws about the magnitude and properties of resistance: one is the resistance law r = ·l s; The other is that the resistance is linearly related to the temperature at high temperaturesr=r0(1+ t), where is the resistivity of the conductor, and is the temperature coefficient

6. Resistance temperature coefficient:

It is a coefficient that represents the degree of change in the resistance value of the thermistor for every 1 oC change in temperature, which is expressed by =1 r·dr dt, and is calculated as: = 1 r·dr dt 100 = -b t2 100

Where: Resistance temperature coefficient %

r: the value of resistance at the absolute temperature t k

b: b value k

b，59ω

The impedance transformation effect of the transformer, the impedance ratio is the square of the transformer ratio. Therefore, the equivalent resistance of the primary side of the transformer = 3 6 = 54.

rab=5ω+54ω=59ω

The figure is described as a three-point vibration.

Swingers. The conditions for a three-point oscillator to satisfy phase equilibrium are:

The two reactive elements connected to the emitter of the transistor must be of the same nature, while the reactive element not connected to the emitter has the opposite reactive properties of the former.

The answer should be c

The circuit is in a common base electrode configuration.

E series inductance L1 to B through capacitor C1

E through the capacitor C1 series inductance L2 to C

There is only capacitance C between b and c

Electrician topic. There are two capacitors, C1 is 200V and 20 F, and C2 is 250V and 2 F, and they are connected to a 400V DC circuit in parallel

A is chosen because the withstand voltage of both capacitors is much lower than 400V.

The voltage of the leakage equipment to the ground before troubleshooting is (, and the calculation method is as follows.

A, two capacitors in parallel, the voltage at both ends and the voltage connected are the same, both are 400V, C1 and C2 are broken.

There are a large number of electrician test questions, if you are interested, you can take a look.

2. Choose d, because (ab) = (a + b).

3. F=B, the process is shown in the attached figure:

A1 is the only in-phase proportional magnification of blind eggplant cultivation and grinding, and the silver is accepted.

AZ is the differential input enlargement, and the process analysis is shown in the attached figure.

I've forgotten it for a long time. To give you some ideas, l, c are the original of the opposite properties, and I can't remember the formula for the subtraction of their two sets of formulas, as if it were.

The total voltage = resistive voltage + (inductance voltage - capacitance voltage) can be calculated as problem one.

Inductors and capacitors are the original components of energy storage, they are all reactive power, and active power is only considered resistance.

The apparent power formula was forgotten.

It's like a glass of beer with liquid beer in it, and beer foam, and liquid beer is active power.

Foam is reactive power, and the height you see of the overall beer plus foam is the apparent power.

Applying the superposition theorem, when is1 acts alone, us2 is short-circuited, i3'=is1 x (r1 r2) (r1 r2 + r3).

x 12 20=, when us2 acts alone, is1 is open, i3"=6 (r2 + r1 and r3) x r1 (r1+r3).

6/(250/7) x 20/28=，i3=i3'+i3"=。