The Difference Between mA and A, and Their Conversion

In the world of electricity and electronics, understanding the basic units of electrical current is fundamental. The Ampere (A) and the Milliampere (mA) are two critical units that form the backbone of electrical measurements.

This article today sheds some light on these units, illustrating their differences, measuring techniques, safety limits, real-world applications, and conversion methods.

What Is Ampere?

The Ampere, or A, is the base unit of electric current in the International System of Units (SI). It is named after André-Marie Ampère, a French physicist and mathematician who was one of the founders of the field of electrodynamics. An Ampere is defined as the amount of electric charge passing a point in an electric circuit per unit time, with one Ampere equal to one coulomb of charge passing through a given point in one second. This unit underpins the measurement of electric current, reflecting the rate at which electric charge flows.

What Is Milliampere?

A Milliampere, denoted as mA, is a subunit of the Ampere, representing one-thousandth of an Ampere (1 mA = 0.001 A). This unit is widely used in applications where the electric currents involved are relatively small. For instance, the current flowing through a power station or a smartphone charger is often measured in milliamperes. The adoption of the milliampere as a unit of measurement allows for greater precision when dealing with low-current scenarios, which are common in modern electronic devices and circuits.

How to Convert A to mA

Converting Amperes to Milliamperes is straightforward, relying on the basic relationship that 1 A = 1000 mA. To convert, simply multiply the number of Amperes by 1000. For example, if an electrical device draws a current of 2 A, this is equivalent to 2000 mA. This conversion is essential in fields such as electronics, where precise measurements of current are critical for the design and analysis of circuits.

To facilitate the conversion from Amperes (A) to Milliamperes (mA), a detailed table is provided below:

Ampere (A) Milliampere (mA) Description
0.001 A 1 mA Current typical of very low-power devices.
0.01 A 10 mA Common for small sensors and electronic components.
0.1 A 100 mA Typical for LED lighting and circuit boards.
0.5 A 500 mA Standard USB 2.0 port maximum output.
1 A 1,000 mA Charging current for many smartphones.
2 A 2,000 mA Fast charging for modern smartphones and tablets.
5 A 5,000 mA Common for larger electronic devices, such as laptops.
10 A 10,000 mA Small household appliances and tools.
15 A 15,000 mA Typical household circuit breaker rating.
20 A 20,000 mA Heavy-duty electrical tools and appliances.

How to Convert A to Other Units of Electric Current

From Unit (A) To Unit Conversion Factor Description
1 Ampere (A) Milliamperes (mA) 1 A = 1,000 mA Commonly used in electronics.
1 Ampere (A) Microamperes (μA) 1 A = 1,000,000 μA Used for small currents in circuits.
1 Ampere (A) Nanoamperes (nA) 1 A = 1,000,000,000 nA For very small currents in microelectronics.
1 Ampere (A) Kiloamperes (kA) 1 A = 0.001 kA For large currents in industrial applications.
1 Ampere (A) Abampere (abA) 1 A = 0.1 abA CGS system (Electromagnetic units).
1 Ampere (A) Statampere (statA) 1 A ≈ 3.335641×10^10 statA CGS system (Electrostatic units).
1 Ampere (A) Gilbert (Gi) 1 A ≈ 1.256637 Gi Relates magnetic flux to magnetic field.

How to Measure Ampere & Milliampere?

Measuring electric current, whether in Amperes or Milliamperes, typically involves using a device known as an ammeter. An ammeter is connected in series with the circuit whose current is to be measured, allowing the entire current to flow through the device. Digital multimeters, which can function as ammeters, voltmeters, and ohmmeters, are commonly used tools for this purpose. They offer the advantage of being able to measure currents across a wide range of magnitudes, from milliamperes up to several amperes, depending on the specific model and settings.

the tools to measure Ampere & Milliampere

How Does Current Measurement Differ Between AC and DC Circuits?

In DC circuits, current flows in one direction, making it straightforward to measure using a multimeter or ammeter by simply connecting it in series with the circuit. In AC circuits, however, the current changes direction periodically, which requires using a True RMS (Root Mean Square) multimeter for accurate measurements. True RMS multimeters can accurately measure the effective current in AC circuits, regardless of the waveform shape, ensuring precise readings for both simple and complex signals.

The relationship is encapsulated by Ohm's Law, which serves as a cornerstone principle. Ohm's Law states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them. This principle can be expressed with the formula:


Note that I is the current in Amperes (A); V is the voltage in Volts (V); R is the resistance in Ohms (Ω).

Influence of Voltage on Current:

When the voltage (V) across a conductor increases, the current (I) through the conductor also increases, assuming the resistance (R) remains constant. Conversely, a decrease in voltage results in a decrease in current.

Influence of Resistance on Current:

An increase in resistance (R) in a circuit, with the voltage (V) held constant, leads to a decrease in the flow of current (I). Reducing the resistance allows more current to flow through the circuit, given a constant voltage.

How Many Milliamperes or Milliamps Are Safe?

The safety threshold for electric currents passing through the human body varies, but it is broadly accepted that currents above 10-20 mA can be harmful, with the risk of severe injury or death increasing with current strength. Currents as low as 1 mA can be felt, while currents between 10 mA to 30 mA may induce muscle contractions strong enough to prevent the person from breaking free from the source of electricity. This emphasizes the importance of handling electrical devices with care, especially in wet conditions or environments where the risk of electric shock is heightened.

Using a charger with a higher mA rating than what your device specifies can potentially damage the device's battery or circuitry due to excessive heat generation or overcharging. Devices are designed to draw only the required amount of current, but a significantly higher current supply might overwhelm the device's built-in protections, leading to damage or reduced battery life.

How Do Professionals Ensure Safety When Working With Currents That Are Potentially Harmful to Humans?

Professionals ensure safety by using insulated tools, wearing protective gear, and following strict safety protocols when working with electrical currents, especially those exceeding the 10-20 mA threshold considered potentially harmful to humans. Additionally, electrical systems are designed with safety features such as circuit breakers and ground fault circuit interrupters (GFCIs) to automatically cut off power in case of an overload or short circuit, reducing the risk of electric shock.

Real-World Applications of Ampere & Milliampere

Amperes and milliamperes find applications in virtually all devices and systems that use electricity. For high-power applications such as electric motors in industrial machinery, currents are typically measured in amperes. In contrast, delicate electronic devices like portable power stations, laptops, and wearable technology primarily operate within the milliampere range. The distinction between these units is crucial for designing, testing, and troubleshooting electrical and electronic systems, ensuring they operate safely and efficiently.

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Final Words

Understanding the difference between Ampere and Milliampere, along with their measurement, safety considerations, applications, and conversion, is fundamental for anyone involved in electrical engineering, electronics, or related fields. This knowledge not only facilitates accurate and safe electrical measurements but also enables the effective design and operation of electrical and electronic systems. As we continue to innovate and rely more on electrical devices, the importance of these basic units and the principles behind them remains undiminished, underlining the need for a clear and comprehensive grasp of electrical current measurements.

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