Physical voltage, how to understand the physical quantity of voltage

d It's too simple. a voltage depends on the power supply, the power supply has electricity, there is voltage, and the current is generated by the voltage, there is not necessarily a current, but if there is a current, there must be a voltage.

b. Although the range is large and will not be burned out, sometimes in the experiment, the exact voltage is measured, and the measurement is inaccurate when the range is large, so it depends on the situation.

c. There is voltage and there is not necessarily a current As mentioned above, the current needs to be generated by a circuit with a path.

d The voltage in parallel is equal everywhere The book says, If you don't understand, you can ask me or ask your teacher.

A error. There is a potential difference in the power supply, such as a battery that is not connected to the circuit.

b false, in order to ensure a better reading, the appropriate range should be selected.

c error, for example, there is voltage at both ends of the bulb that is not turned on, but the bulb does not light up, that is, there is no current flowing through the bulb.

d。The voltages in the parallel circuit are equal.

Correct answer: d

a The voltage of the power supply is constant, and the disconnection is not the same.

b If the voltage is only 3V, choose a 10000V voltmeter, and the pointer will not be able to see the deflection error.

c If the circuit is in parallel, there is a branch open circuit, and there is voltage at both ends, but there is no current error in the open branch.

d to the voltage in parallel circuits is equal everywhere (theorem).

a. The power supply voltage is constant.

b. The larger the measuring range, the lower the accuracy.

c. The circuit needs to be connected to have current.

d. U1=U2=U3=......... in parallelThis is the isobaric principle. Pick D

A is incorrect, the power supply voltage is not 0, B answer is also incorrect because the range should be selected according to the need, if the voltage is less than the small range should be selected 0-3V, so that the error is small, C The answer is wrong, there is voltage and there is not necessarily current, and the circuit must also be connected. d is correct, because the voltage at both ends of each branch of the parallel circuit is equal. Give me a reward.

Voltage: As we all know, the reason why water can flow in the pipe is because of the difference between high and low water levels, and the water can flow from high to low. The tap water used in the city can flow out of the pipe as soon as the water gate is opened, because the water storage tower is higher than the ground, or because the pressure difference caused by the water pump.

The same is true of electricity, which is able to flow in the wire, also because there is a difference between high and low potential. This difference is called the potential difference, also known as the voltage. In other words.

In a circuit, the potential difference between any two points is called the voltage at those two points. Voltage with a symbol"u"Denote. The level of voltage is generally expressed in unit volts, referred to as volts, and is symbolized"v"Denote.

High voltages can be expressed in kilovolts (kv) and low voltages can be expressed in millivolts (mv).

The conversion relationship between them is:

1 kilovolt (kv) = 1000 volts (v).

1 volt (V) = 1000 millivolts (mV).

1. For parallel circuits, the total voltage is equal to the voltage of each branch. 2. The voltmeter will divide part of the voltage, but because the resistance is very large, the voltage is very small, and it can be ignored numerically, which is an approximate value, and it cannot be completely accurate.

Landlord,I look a little dizzy on your last two questions.,I can't tell the principle.,I can't give you a verified circuit diagram.,However,I'll give you an indirect understanding method.。 According to my current knowledge of physics, the principle of the circuit and the waterway is basically the same, the voltage difference is equal to the water pressure difference, and the current is equal to the water flow rate ......

Question 4 According to the above understanding, as soon as there is an electric current passing through the branch, it is like a flow of water, no matter how dense you seal the wall, there will be water wading through, if it is a diversion, the water resistance of the two tributaries is the same, then the water flow is the same, that is, the current of electric condolence.

1.Branch voltage = trunk voltage.

2.There will be no voltage splitting. (parallel shunt, series voltage shunt); The voltmeter measures the voltage of the conductor being measured.

1. In the parallel circuit, the current in the trunk circuit is the sum of the currents in each branch.

2. The ammeter is connected in parallel on the conductor, because the current resistance is very small, and it is connected in parallel on the conductor (series voltage division, parallel shunt), so part of the voltage cannot be separated.

3. The circuit diagram of measuring the relationship between voltage, current and resistance is to observe the current change through the resistance through the change of the voltage applied to both ends of the resistor, and find out the relationship between voltage, current and resistance, that is, r=u i, u=ri, i=u r.

1.The first empty negative electrode.

The second empty positive pole.

The third empty voltage difference.

Fourth hole u

The sixth empty power supply.

The seventh empty v

The eighth empty 5v

The ninth empty 220v

Tenth empty 36v

2.The first no-voltage voltage.

The second null v

The third null is connected in parallel.

The fourth empty +

The fifth empty -

The sixth space is the maximum range.

3.The first null is equal to.

The sum of the second emptiness.

The third void is equal.

The fourth hole is added.

The fifth null is equal to.

1.Positive Negative Voltage Difference U Formation Current Power Supply Volts 220V Not higher than 36V

These basic questions are available in the book, and the teacher has memorized them, have you learned?

1: Why are the voltages of dry cell batteries equal, but the length of their use and the current generated in the circuit are not equal?

Because their volume is different, the amount of reaction agent contained in them is different. The larger the volume and the larger the volume, the more the charge, the greater the allowable discharge current, and the more durable it is.

2: Why is the voltmeter connected in parallel?

The voltmeter can only measure the voltage at both ends of the tested circuit in parallel, and the circuit cannot work because the internal resistance of the voltmeter is too large.

3: The difference between a broken filament and an open circuit bulb [** where the current goes to the lamp?] 】

When the filament breaks, there is no current for the lamp to pass through. The bulb is open, maybe the bulb is fine, but there is no normal access to the circuit, maybe the filament is broken, and there will be no current through the bulb lamp circuit.

4: The principle of voltmeter [talk about it carefully].

The voltmeter is a highly sensitive meter head, which is connected in parallel with calibration resistors and in series with upper current resistors. Changing the current limiting resistor and adjusting the full voltage of the meter changes the range.

5: What exactly is voltage [explained from the microscopic level].

The role of the power supply is to act on the charges, causing them to create a potential difference at the output. The voltage is a comparison of the difference in the charged properties at two reference points, that is, the potential difference, and it is not correct to say that the voltage at a certain point alone.

6: If the voltmeter is connected in parallel on the lamp and battery, measure whose voltage.

The voltage at both ends of the lamp is measured. Because the wire resistance is ignored, it can be considered as the battery voltage. Series circuits are a different story.

7: What's the light of the electric light?

When the lamp is energized, there is an electric current passing through the filament, which generates heat on the filament. The filament glows when the temperature exceeds 500 and glows white when it exceeds 2000.

There are also fluorescent lamps, metal halide lamps, LED lamps, etc.

Fluorescent lamps use mercury vapor to produce ultraviolet light, which excites phosphors to emit light. Different formulations of phosphors emit different light colors.

Metal halide lamps and high-pressure sodium lamps emit light using gas discharge.

LED is a semiconductor material, and its luminescence mechanism is also different from that of incandescent lamps, with high luminous efficiency, which can be made into white or red, green, blue, violet, and even ultraviolet, infrared and laser.

Physics and electricity in junior high school is ideal electricity, and many factors are not considered. For example, the voltmeter is regarded as an open circuit, the ammeter is regarded as a short circuit, the wire does not count the resistance value, and the power supply has no internal resistance.

1. The electrode reaction of the dry battery is as follows: the zinc atom at the negative electrode becomes zinc ion (Zn++) to release electrons, and the ammonium ion (NH4+) at the positive electrode gets electrons and becomes ammonia and hydrogen. Hydrogen is driven away with manganese dioxide to eliminate polarization.

The electromotive force is about volts (voltage volts). It's okay to know this, and the exam won't delve into it.

2. Because the resistance of the voltmeter is extremely large, if it is connected to the series circuit, it is equivalent to an open circuit.

3. Current route: the filament that flows into the bulb from the wire (the filament is also equivalent to the wire), and then flows out and continues into the wire. You can also think of it this way: the filament is part of the wire. Therefore, if the filament is broken, it is an open circuit, and there is no difference.

4. For example, if the interface is A and B, there is a resistor R between AB, and the voltmeter measures the current through A and B. The current passes through the small magnetic needle in the voltmeter, because the electricity has a magnetic effect, the larger the current, the stronger the magnetism, and the larger the indicator. Because the voltmeter resistance does not change, the higher the current, the greater the voltage.

Understandable, right? ）

5. Encyclopedia explanation: Voltage, also known as potential difference or potential difference, is a physical quantity that measures the energy difference between a unit charge in an electrostatic field due to different electric potentials. Its magnitude is equal to the unit of work done by a positive charge to move from point A to point B due to the force of the electric field, and the direction of the voltage is specified as the direction from the high potential to the low potential.

The SI system of units for voltage is volts (V), and commonly used units include millivolts (mV), microvolts (V), kilovolts (kV), etc. This concept is similar to the "water pressure" caused by the high and low water level. It should be pointed out that the term "voltage" is generally only used in electrical circuits, while "potential difference" and "potential difference" are generally applied to all electrical phenomena.

According to my understanding, it is the force that pushes the electric current, and I don't understand much about the microscopic perspective.

6. The total voltage is the lamp voltage plus the power supply voltage.

7. Encyclopedia explanation: When the current passes through the filament (tungsten filament, the melting point is more than 3000), the spiral filament continues to gather heat, so that the temperature of the filament reaches more than 2000, and the filament emits light when it is in an incandescent state, just like the red-hot iron can shine. The higher the temperature of the filament, the brighter the light emitted.

Therefore, it is called incandescent lamp.