Volt, Ampere, Watt, how are these three terms to be understood?
Volts represent the basic unit of voltage, or volts for short. Symbol V.
Named in honor of Italian physicist Volt.
The three most basic units in electricity are voltage (V), current (I), and resistance (r). The units of voltage are volts, the units of current are amps, and the units of resistance are ohms.
Volt: The unit of voltage in V
Ampere: The unit of current in A
Watt: The unit of power in W
Power W=Voltage V*Current A
How to distinguish the ammeter, voltmeter and ohmmeter in the multimeter?
The ammeter measures current, with the symbol “A”; the voltmeter measures voltage, with the symbol “V” or “kV”; the ohmmeter measures resistance, with the symbol “Ω”
How the photovoltaic effect occurs
1. Photovoltaic effect refers to the phenomenon that light causes a potential difference between different
parts of uneven semiconductor or semiconductor and metal bonding. It is firstly the process of converting photons (light waves) into electrons and light energy into electric energy; secondly, it is the process of forming voltage. With voltage, it is like building a dam. If the two are connected, a current loop will be formed.
2. Photovoltaic materials are materials that can directly convert solar energy into electrical energy. Photovoltaic materials are also called solar cell materials, and only semiconductor materials have this function. Materials that can be used as solar cell materials include monocrystalline silicon, polycrystalline silicon, amorphous silicon, GaAs, GaAlAs, InP, CdS, CdTe, etc. For space there are single crystal silicon, GaAs, InP.
3. Monocrystalline silicon, polycrystalline silicon and amorphous silicon have been mass-produced for the ground. Others are still in development. Currently, efforts are being made to reduce material costs and improve conversion efficiency, so that the electricity price of solar cells can compete with that of thermal power generation, thereby creating conditions for wider and larger-scale applications.
4. The non-electrostatic force of the photoelectromotive force (photocell) comes from the internal photoelectric effect. Under illumination, if the energy of the incident photon is greater than the forbidden band width, the bound valence electrons near the PN junction of the semiconductor absorb the photon energy and are excited to transition to the conduction band. Free electrons are formed, and correspondingly free holes are formed in the valence band. These electron-hole pairs, under the action of the internal electric field, the holes move to the P region, and the electrons move to the N region, so that the P region is positively charged, and the N region is negatively charged, so a voltage is generated between the P region and the N region, It is called photoelectromotive force, which is the photovoltaic effect. Sensitive elements made of photovoltaic special effects include photocells, photodiodes, and phototransistors.
What is the total current in the circuit? What about the current and voltage of each branch?
The total current of the circuit is required, and the total resistance of the circuit needs to be calculated first.
In this circuit, there is a 5-ohm resistor and a 3-ohm resistor in parallel, so first find the parallel resistance of these two resistors, and then add the 10-ohm resistor in series to find the total resistance of the entire circuit, The total current in the circuit can then be obtained by dividing the supply voltage by the total resistance.
Then multiply the total current by the resistance of ten ohms to get the voltage across the resistor, and then subtract ten ohms from the power supply voltage, and the voltage of the resistor can be used to find the voltage of the parallel circuit. With the voltage of this parallel circuit, and then multiplying it by the resistance of three ohms, the current of the resistance of three ohms can be calculated, and then multiplying the voltage of the parallel circuit by the resistance, the current of the resistance of five ohms can be calculated.
Total current i=20/[10+(5 and 3)]=20/[95/8]=32/19 A.
Is the total voltage of a parallel circuit equal to the sum of the voltages of the branches?
The power supply voltage of a parallel circuit is not equal to the sum of the voltages of the branches. In a parallel circuit, the voltages of the branches are equal, and the power supply voltage is equal to the voltage of the individual branches connected in parallel to the power supply.
The voltage of the parallel circuit is equal to the voltage of each branch, and the current of the parallel circuit is equal to the sum of the current of each branch.
Electric Boat Lithium Iron Phosphate Battery Voltage (Volt)
Type Power Nominal Voltage Nominal Capacity
Fishing boat: Electricity: 49.5kWh, nominal voltage 352.8V, nominal capacity 140.4Ah
Speedboat: Power: 92kWh, nominal voltage 655.2V, nominal capacity 140.4Ah
Yacht: Power: 93.5kWh, nominal voltage 345.6V, nominal capacity 270Ah
Sightseeing boat: Power: 62.9kWh, nominal voltage 151.2V, nominal capacity 416Ah
What is the voltage of household appliances?
Heating and cooling air conditioner: 150V-265V, constant speed: 185V-265V.
Washing machine: 175V-265V.
At present, there are generally two types of voltages used for indoor electricity in countries around the world:
They are 100V~130V, and 220~240V two types.
100V, 110 ~ 130V are classified as low voltage, such as the United States, Japan, etc. and the voltage on board, so its equipment is designed according to such low voltage, focusing on safety.
Common voltage values
- The voltage induced by the TV signal on the antenna: about 0.1mV
- Voltage to maintain human biocurrent: about 1.2mV
- Alkaline battery nominal voltage: 1.5V 
- Voltage between the two poles of silver oxide battery for electronic watch: 1.5V
- One lead-acid battery voltage: 2V 
- The voltage between the two poles of the battery of the hand-held mobile phone: 3.7V
- Human body safety voltage: not higher than 36V 
- Household voltage in Japan and some American countries: 110V
- Voltage of home circuit: 220V
- Power circuit voltage: 380V
- Voltage of trolleybus power supply: 550~600V
- Working voltage of TV picture tube: above 10kV
- Grid voltage above the train: 25kV 
Voltage between clouds where lightning occurs: up to 1000kV
The simple answer is NO. Voltage is just pressure and poses no danger. In fact, when you get a spark off your finger from static electricity, the voltage of that spark is usually around 25,000 volts!
We have all seen this sticker but it’s a bit of a misnomer. The high voltage is not dangerous, but the circuit also has a high current which is dangerous. You need both high voltage and current to be dangerous.
Since voltage is only a measurement of pressure, there needs to be enough electrons to flow to be dangerous. With enough pressure and flow (amps) an electrical circuit can become dangerous. Any circuit below 50 volts will not have enough electrical pressure to push enough current through your body to cause harm.
Introduction to the classification of voltmeters
Analog Electronic Voltmeter
The analog electronic voltmeter generally uses a magnetoelectric ammeter head as an indicator. Since the magnetoelectric ammeter can only measure DC current, when measuring DC voltage, it can be directly amplified or attenuated into a certain amount of DC current to drive the pointer of the DC meter head to deflect to indicate its size; when measuring AC voltage, it must pass through AC – DC converter, which converts the AC voltage to be measured into a DC voltage proportional to it, and then measures the DC voltage.
In the analog electronic voltmeter, most of them use the rectification method to convert the AC signal into a DC signal, and then indicate the reading through the DC meter. This method is called the detection method; in addition, there are thermocouple conversion methods and formula conversion methods.
The digital voltmeter first uses the analog/digital (A/D) conversion principle to convert the measured analog voltage into the corresponding digital quantity, and directly display the measured voltage value in digital form. Compared with the analog voltmeter, the digital voltmeter has the advantages of high precision, fast measurement speed, strong anti-interference ability, high degree of automation, and easy reading.
The most basic and common digital voltmeter is the DC digital voltmeter (DVM), which can measure AC voltage, current, resistance and other electricity with different converters or sensors at its input. It is an essential part of many digital measuring instruments.