Voltage, Current, Resistance
Voltage: Voltage is the presser which force the electrons to flow in a particular direction in a conductor. The unit of voltage is Volt and denoted by V. Battery is a good source of voltage. 3V, 3.3V, 3.7V and 5V are most common in electronic circuits and devices.
Current: Current is the flow of electrons in a particular direction. More formally, current is the rate of change of electron in a particular direction. Unit of current is Ampere and denoted by I. In electronic circuits current is in milliampere range (1 Ampere = 1000 milliampere). For example, typical current for an LED is 20mA.
Voltage is the cause and current is the result.
Resistance: Resistance is the hindrance to the flow of charge or electron. The unit of resistance is The SI unit of electrical resistance is the ohm (Ω).
There is an important relationship among these three quantity voltage, current and resistance:
V = IR or I = V / R or R = V / I
This relation is called Ohm's Law. Voltmeter, ammeter and ohm meter is used to measure voltage, current and resistance respectively.
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