Milliampere, or milliamp: 1/1000 of an Ampere. Ampere is the basic unit for measuring electrical current.
What is a Milliampere Equal To?
The “Ampere”, usually abbreviated as “Amp” in spoken language, is the SI unit of electrical current and has the written symbol A. Electronic components usually use currents that are less than 1 Amp. Engineers use engineering notation (a subset of scientific notation) to avoid using fractions. Instead of using terms like 0.5 Amps or 0.01 Amps, it is more convenient to express small currents as multiples of “milliAmps”.
One milliAmp is equivalent is one thousandth of an Amp. For example, 0.1 Amps is equivalent to 100 milliAmps and 0.01 Amps is 10 milliAmps. While the term “milliAmp” is used in spoken communication, it is abbreviated as mA in writing. A Light Emitting Diode or LED (Figure 1) typically used to indicate if a piece of equipment is switched on or in standby will normally use between 10 and 30 milliAmps.
Figure 1. LED standby indicator
What is a microAmpere?
A microAmpere (usually abbreviated as microAmp in spoken language) is one thousandth of a milliAmp or 1 millionth of an Amp. 1 microAmp is abbreviated in writing as 1 µA. The symbol “µ” (pronounced “mew”) is from the Greek Alphabet. As electronic components have shrunk in size, the amount of current they use has also got smaller, even less than 1 mA. Currents that are smaller than 1mA are usually referred to in multiples of microAmps. For example, 0.1 mA is equivalent to 100 µA. Electronic components that use currents less than 1mA are often referred to as microelectronic components or devices. An example would be a single transistor on a silicon chip. The symbol for a transistor is shown in Figure 2.
Figure 2. Transistor Symbol
What Does Milliampere Stand For?
The term milliAmp is commonly used when specifying the capacity of a battery. For example, the capacity of a mobile phone battery (Figure 3) might be 3000 milliAmp – hours (written as 3000 mAh). This means the battery can supply 3000 mA for 1 hour or 6000 mA for 30 minutes or 1000mA for three hours etc. In other words, the more current that is used by the phone, the shorter the length of time the battery will last.
Figure 3. 3000mAh Mobile Phone Battery
What is the Meaning of mA in Electricity?
Electricity companies charge customers for electricity by the amount of current they use called “units”. One unit of electricity is 1 kilowatt-hour (in the U.S, this equates to approximately 10 Amps per hour). The number of units used is recorded on an electricity meter (Figure 4). Readings are made, usually monthly or bimonthly, and consumers are then billed for their usage.
Figure 4. Electricity Meter
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