Question

One ampere is equal to how many milliamperes?
A. ${10^{ - 16}}$
B. ${10^{ - 3}}$
C. ${10^3}$
D. ${10^6}$

Answer 1

Hint: An ampere is a unit used to measure the rate of flow of electrons or current in an electrical conductor. One ampere is known as the one coulomb of charge moving in one second. Milli ampere is the unit of calculation of the flow of current equal to the ampere divided by the thousand.

Complete step by step answer:
An ampere is defined as the unit of electric current. The name ampere comes from the name of French-physicist and mathematician, also known as the father of physics, Andre-Marie Ampere. One ampere is known as the one coulomb of charge moving in one second.
The milliampere is the unit of electric charge which is equal to the ampere of the charge divided by the thousand which is given by
$1A = \dfrac{1}{{1000}}mA$
$ \Rightarrow 1A = {10^{ - 3}}mA$
$\therefore 1A = {10^{ - 3}}mA$
Hence, option B is the correct option.

Additional Information:
We can also convert the unit Ampere into kilo amperes and microamperes which as shown below;
Kilo amperes: It is the unit of electric current which multiplied by the thousand. Therefore, kilo ampere is the unit which is equal to the thousands of ampere which is given by
$1kA = 1000A$
$ \Rightarrow \,1kA = {10^{ - 3}}A$

Microampere: It is the unit of electric current which is multiplied by $1000000$ or ${10^6}$ . Therefore, the microampere is the unit which is equal to $1000000$ or ${10^6}$ of ampere which is given by
$1\mu A = 1000000A$
$ \Rightarrow \,1\mu A = {10^6}A$

Note:In the past times, the definition of ampere was different. It was defined as the one-tenth of the unit of electric current flowing in a centimetre gram second (CGS) system of units. Nowadays, those units are known as abampere.