Current Formula | Current calculations

The electrical current through any conductor is defined as the rate of flow of charges. The current formula is defined as the ratio of charge Q to the time t. Mathematically

Formula to calculate current: I = Q/t

Where in above equation:

I = Current [measured in amperes]

Q = Charge [in coulombs]

t = time [seconds]

Also, learn about the formula for voltage.

Current formula calculator

The formula below can be used to calculate amps from coulomb per unit time.


Example Calculations

Example # 1: If 10 C charge passes through an area in 5 s. Find the current flowing through that surface.


Q = 10 C

t = 5 s

I = Q/t = 10 C / 5 s = 2 A

Current [A] Charge [C] Time [s]
2 A 10 C 5 s
0.38 A 3.8 C 10 s
0.2 A 1 C 5 s
9 A 18 C 2 s
5 A 50 C 10 s


Let’s consider a copper conductor which contains a large number of free electrons that are randomly moving within it. The application of external potential difference moves the electrons from the negative terminal of the battery to the positive terminal. This motion of electrons causes the electric current to flow from one point to the other.

Conventional vs Electron flow

We previously observed that flow of current is actually the flow of electrons from one terminal of the battery to the other. The current which flows due to movement of the electron is termed as electron current.

Very often another term conventional current flow is used. It actually represents the flow of current from the positive terminal of the battery towards the negative terminal of the battery.

Let’s summarize our discussions visually:


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