Measuring Electric Current

Table of Contents

• SI Unit of Current
• Measuring Electric Current
• Summary
• What’s Next?

In the previous segment, we learnt about electricity. In this segment, we will understand how electric current is measured.

What is the SI unit of current?

• Electric current is defined as the rate of flow of electric charge.
• If a net charge ‘Q’ flows across any cross-section of a conductor in time ‘t’, then the

electric current I through that cross-section is given by

• The SI unit of charge is coulomb (C).

? =

?.

?

• This is the charge contained in approximately 6.24 × 10¹⁸electrons.
• The SI unit of time is seconds.
• Hence, the SI unit of current will be Coulomb per second, which is called Ampere, named after the French scientist Andre-Marie Ampere.
• Ampere is defined as the current generated due to the flow of one coulomb of charge in one second.

1 ? =

1 ?

.

1 ???

• Small quantities of current are expressed in milliamperes or microamperes.

How is Electric current measured?

• Electric current is measured using an Ammeter.
• An ammeter is connected in series with the cell and then the plug key is closed. As the key is closed, the current starts to flow through the circuit and the ammeter, which measures the electric current flowing through it.