Question

A current of 1 microampere is drawn by a device for three hours. Find the amount of electric charge that flows through the circuit.

Answer 1

Hint: Current and time of flow of current is given. To find the amount of charge flowing, use the relation between current, time and charge.

Formula used: I.t = Q, where I is the amount of current flowing, t is the duration of flow of current and Q is the charge that flows.

Complete step by step answer:
One coulomb is equal to the amount of charge from a current of one ampere flowing for one second.
We are given with-
Current = 1 micro ampere
Time = 3 hours
 An electric current exists when there is a net flow of electric charge through a region. Electric charge is carried by charged particles, so an electric current is a flow of charged particles.
Since we know that, current is defined as the charge flow per unit time,
I = $\dfrac{{\text{Q}}}{t}$ .
And Q = I.t
Q = ( 1 micro ampere) x (3 hours)
     $
   = (1 \times {10^{ - 6}}) \times (3 \times 60 \times 60) \\
   = (3 \times 3600 \times {10^{ - 6}}) \\
   = (10800 \times {10^{ - 6}}) \\
   = 10800{ \mu C} \\
   = 0.0108{\text{ C}} \\
 $

The amount of charge flowing is 0.0108 Coulombs.

Note: The charge is a scalar quantity as it has only magnitude and no direction. The charge is just as other fundamental properties of the system like mass. The only difference between mass and charge is that charge is both positive and negative, while mass is always positive. Whenever current flows through any conducting material it heats the material.