Formula for electric current in basic SI units Which expression correctly relates electric current to the amount of charge that passes a point over a given time interval?

Introduction / Context:
Foundational circuit analysis relies on clear relationships among voltage, current, charge, time, and resistance. The definition of current in terms of charge and time appears in both physics and engineering curricula and underpins units like the ampere and coulomb.

Given Data / Assumptions:

• No numeric values are given; only the correct algebraic form is required.
• Current I is in amperes (A), charge Q in coulombs (C), and time t in seconds (s).

Concept / Approach:
By definition, electric current is the time rate of flow of charge: I = dQ/dt. For average current over a finite interval, I = Q / t. Dimensional analysis confirms that C/s equals A, the SI unit of current.

Step-by-Step Solution:

Verification / Alternative check:
Alternative forms appear in integral or differential statements, but the average formula remains Q/t. This aligns with typical lab measurements where total charge transfer and elapsed time are recorded.

Why Other Options Are Wrong:

• charge × time or time / charge: neither matches A = C/s.
• voltage × time: has units of volt-second (weber-equivalent context), not current.

Common Pitfalls:
Confusing voltage and current relationships or inverting the ratio (t/Q). Always perform a quick unit check to catch errors.

Final Answer:
charge / time