F.2 IS -電流(current)和電壓(voltage)有甚麼分別?

可以考慮這樣理解 :

electron = 電子 (如水滴, 水點)

current = 電流 (如水流)

voltage = 電壓 (如瀑布的水位差出現的水壓)

想像一下這三者的關係吧!

1. Electric Current
1.1 Current is by definition the flow of electric charge. The SI unit of electric current is the ampere (A), which is equal to a flow of one coulomb of charge per second.

1.2 The magnitude of an electric current is defined as the time derivative of electric charge
I = Q / t
, where
Q is the electric charge in coulombs (ampere seconds);
t is the time in seconds


2. Voltage
2.1 Voltage is the difference of electrical potential between two points of an electrical network, expressed in volts [1]. It is a measure of the capacity of an electric field to cause an electric current in an electrical conductor.

2.2 Between two points in an electric field, such as exists in an electrical circuit, the difference in their electrical potentials is known as the electrical potential difference. This difference is proportional to the electrostatic force that tends to push electrons or other charge-carriers from one point to the other. Potential difference, electrical potential, and electromagnetic force are measured in volts, leading to the commonly used term voltage. Voltage is usually represented in equations by the symbols V, U, or E. (E is often preferred in academic writing, because it avoids the confusion between V and the SI symbol for the volt, which is also V.)

2.3 Electrical potential difference can be thought of as the ability to move electrical charge through a resistance. At a time in physics when the word force was used loosely, the potential difference was named the electromotive force or emf—a term which is still used in certain contexts.

2.4 Voltage is a property of an electric field, not individual electrons. An electron moving across a voltage difference experiences a net change in energy, often measured in electron-volts. This effect is analogous to a mass falling through a given height difference in a gravitational field.

2.5 When using the term 'potential difference' or voltage, one must be clear about the two points between which the voltage is specified or measured. There are two ways in which the term is used. This can lead to some confusion.


3. Relationship
3.1 The relationship between current and voltage can be expressed by Ohm's Law

3.2 Ohm's law predicts the current in an (ideal) resistor (or other ohmic device) to be applied voltage divided by resistance:
I = V / R
, where
I is the current, measured in amperes
V is the potential difference measured in volts
R is the resistance measured in ohms