Voltage drop, also known as voltage or potential difference, is expressed as U, unit voltage (V), which is a physical quantity describing the power of electric field force to move charge.
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When the charge flows, the energy possessed by the charge is released in the circuit, and the circuit and the connected components in the circuit will absorb the energy of the charge. After energy absorption, the energy contained in the charge release energy itself becomes smaller. People use voltage drop to measure the ability of the charge to release energy in the circuit. When the current flows through the circuit, a certain voltage drop will be generated in each small section of the circuit. The voltage drop represents the amount of electric energy released (or absorbed by the small section of the circuit) by the charge flowing through the small section.
Voltage drop Voltage 。 The voltage between two points refers to the work done when the unit positive charge passes through these two points under the action of the power supply. Voltage units and emf The same is true Volts (V for short, expressed by the English letter V). Calculation formula of voltage drop between two points: U=W/q
Where, W is the work done by the electric field force to move the charge, q is the positive charge moved by the electric field force
The reference direction of voltage drop is indicated by "+" "-" polarity or double subscripts. The actual direction of voltage is defined as the direction in which the electric field force moves the positive charge to do work, from the high potential end ("+" polarity) to the low potential end ("-" polarity), that is potential Direction of lowering. Voltage drop can also be called Potential difference 。 When the potential of a point is zero, the voltage of any point in the circuit to the reference point is the potential (U) of that point. The potential difference between two points is also the voltage drop between two points. [1] 
