High School Physics

Physics Numericals on electric charge current x time

In this post, we will solve a set of Physics Numericals on electric charge and its current, time relationship.

Formulas Used

Current is a rate of flow of electric charge. Electric charge is measured in coulombs (C). We now know that an electric current is actually a flow of electrons from negative to positive.
Electric current is measured in amperes (A). This is often abbreviated to amps.

The formula that states the relationship between electric current, charge, and duration of electric charge flow is given as follows.

electric charge = current × time
Q =I x t

Numerical Problems on current and charge relationship [solved]

1) A current of 1.2 A flows for 30 s. How much charge flows?


Q = It = 1.2 × 30 = 36 C

2) Calculate the current when 80 C of charge flows in 16 s.


Q = It
=>I = Q/t = 80/16 A = 5 A

3) A current of 6 A builds up a charge of 96 C. Calculate how long the current flows.


Q = It
=>t = Q/I = 96/6 = 16 s.

See also  Internal Resistance of a Cell
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