If the internal resistance Ra of the ammeter is 0.03 ohm and the internal resistance RV of the voltmeter is 2 kiloohm, the resistance R to be measured is about 1.5 kiloohm, and the internal and external connection methods have small error

If the internal resistance Ra of the ammeter is 0.03 ohm and the internal resistance RV of the voltmeter is 2 kiloohm, the resistance R to be measured is about 1.5 kiloohm, and the internal and external connection methods have small error

Obviously, internal connection method is adopted. Reason for selection of internal and external connection method: compare the size of R ^ 2 and ra * RV. If the former is large, it means that the measurement resistance is too large and the shunt of voltmeter is obvious. Internal connection method should be adopted. Otherwise, external connection method should be adopted
Is the resistance of ammeter high or that of voltmeter high
voltmeter
In the experiment of measuring resistance by voltammetry, the ammeter is damaged suddenly. In order to complete the experiment, we use a voltmeter to measure the resistance
The circuit must be connected only once
In addition to the original equipment, we need to add ()
2. Write the main experimental steps
Only a known resistor needs to be connected in series in the circuit
Steps: 1. Connect two resistors in series to the power supply
2. Connect the voltmeter to both ends of the known resistance to measure the voltage at both ends of the known resistance
3. According to Ohm's law, calculate the current through a known resistance
4. Because the resistors are connected in series, the current flowing through is equal. Then the voltage at both ends of the unknown resistor is calculated, and the resistance value of the unknown resistor is calculated according to Ohm's law
If the internal resistance Ra of the ammeter is 0.02 ohm, the internal resistance RV of the voltmeter is 2000 ohm
If the resistance R to be measured is about 3 Ka ohm, which connection method has less error? If the resistance R to be measured is about 2 Ka ohm, which connection method has less error?
R ^ 2 = 9000000 ra * RV = 40R ^ 2 > ra * RV adopts the internal connection method of ammeter, and the error is small. If the resistance R to be measured is about 2K Ω, the internal connection method of ammeter has small error. It is wrong. It seems that if the resistance R to be measured is about 2 Ω (reasonable) R ^ 2 = 4 < ra * RV = 40
What is the physical meaning of joules per second?
Yes, from the perspective of thermodynamics, there is such a combination of units. If Joule is regarded as a measure of heat or work, and the heat or work as a process quantity is related to time. Q or W in thermodynamics is often a function of multiple parameters. In the transient analysis of practical problems, the first and second partial derivatives of heat or work to time will be widely used, The unit of the second partial derivative is joule per square second
If the sliding rheostat is short circuited or open circuited in the circuit for measuring the power of the bulb, what will happen to the bulb and the voltmeter and ammeter
1. If the sliding rheostat is open in this circuit, what changes or no changes in the brightness of the bulb, the indication of the voltmeter and ammeter?
2. If the sliding rheostat is short circuited in this circuit, what changes or no changes in the brightness of the bulb, the indication of the voltmeter and ammeter?
3. What are the concepts of short circuit and open circuit of sliding rheostat?
Here's a picture
Our professor seems to say that the light bulb brightness does not change when there is a short circuit?
Please answer completely!
Is the second floor ironic?
Draw a diagram or explain the position of the voltmeter in the circuit, so as to give you a perfect solution
After looking at the drawings drawn by the master draftsman, I have made clear your request for questions
1. If the sliding rheostat is open in this circuit, what changes or no changes in the brightness of the bulb, the indication of the voltmeter and ammeter?
Answer: the circuit is in the open circuit state, and no current passes through. Therefore, the light changes from on to off, and the voltmeter and ammeter change from indication to no indication
2. If the sliding rheostat is short circuited in this circuit, what changes or no changes in the brightness of the bulb, the indication of the voltmeter and ammeter?
A: after the sliding rheostat is short circuited, the loop current increases, the bulb lights up, the voltage of the voltmeter changes into the power supply voltage, and the indication of the ammeter also increases. (Note: if the slide of the sliding rheostat itself is at the position of the minimum resistance, the situation after the sliding rheostat is short circuited is what your professor said, the brightness of the lamp and the indication of the ammeter voltmeter remain unchanged, Because in this case, the short circuit has nothing to do with the circuit.)
3. What are the concepts of short circuit and open circuit of sliding rheostat?
A: short circuit: the circuit resistance decreases, the current increases, the power of the bulb increases, and the brightness becomes stronger
Open circuit: just like the switch to open the circuit, there is no current in the circuit, the lamp will not be on, and the meter will not have indication
Master draftsman, do you understand?
If the actual voltage of the consumer is lower than the rated voltage, what is the actual power rating of the consumer
If the actual voltage of the consumer is lower than the rated voltage, the actual power of the consumer is less than the rated power
The resistivity of an object is 10'6 to 10'8 ohm per meter, which is called insulator or semiconductor?
The resistivity of insulator is 10'8 to 10'18, that of semiconductor is 10 '- 18 to 10' - 8, that of conductor is 10 '- 8 to 10' - 6, and that of semiconductor is 10 -'5 to 10'6
At room temperature, the resistivity can only be used as a rough reference to judge whether the material is metal or insulator
In fact, the resistivity of semiconductors at low temperature is as high as that of insulators; after high doping, the resistivity of semiconductors will be as low as that of metals
For example, diamond is an insulator, but it is also a semiconductor at high temperature
The power of automobile engine is 4kw, which means (). The engine does () Joule work in 10 minutes
The physical meaning of 4 kW engine power is (). The engine does () joules of work in 10 minutes. If the resistance of the car is 200 N, the car will run at a constant speed of () m in 10 minutes
Supplement: the power of automobile engine is 4kw, which means that it consumes 4Kj of energy per second. The engine does (2.4 × 10 ^ 6) joules of work in 10 minutes. If the resistance of the automobile is 200N, the automobile will have a uniform speed of (1.2 × 10 ^ 4) m in 10 minutes
380V voltage, 1kW is how much current? 220V voltage, 1kW is how much current? How to calculate?
Electrician: 220V single phase 1kW 4.5a 380V 1kW 2A