[table]
[tr]
[td][h3]Q[/h3][/td][td]Charge, Coulombs, C[/td]
[/tr]
[tr]
[td][h3]I[/h3][/td][td]Current, A[/td]
[/tr]
[tr]
[td][h3]T[/h3][/td][td]Time, seconds, s[/td]
[/tr]
[/table]
Electrical charge ([b]C[/b])is the amount of electrons in the circuit (the charge).
One [b]Coulomb[/b] contains [b]6.24[multiply]10^18 electrons[/b].
How much and for how long it flows is depends on the other 2 factors, [b]time[/b] and [b]current[/b].
The relationship between the 3 variables is shown by this equation:
[code]
Q = I [multiply] T
[/code]
which can be rearranged to:
[code]
I = Q [divide] T
[/code]
or:
[code]
T = Q [divide] I
[/code]
[h3]Current[/h3]
[u]Current is the rate of flow of charge[/u]
Effects of current:
[ul]
[li]Heating[/li]
[li]Chemical[/li]
[li]Magnetic[/li]
[/ul]
[hr]
Using the formulae, one can find out the values of a desired variable if they possess the other 2.
[h3]Examples[/h3]
[highlight]
[b]Example 1[/b]
[code]
[b]I[/b] = 5mA
[b]Q[/b] = 25mC
[/code]
First convert these into normal numbers:
[b]I[/b] = 5[multiply]10^-3 = [u]0.005 amps[/u]
[b]Q[/b] = 25[multiply]10^-3 = [u]0.0025 coulombs[/u]
[table]
[tr]
[td][b]T[/b][/td][td]=[/td][td style='text-align:left'][b]Q[/b] [divide] [b]I[/b][/td]
[/tr]
[tr]
[td][/td][td]=[/td][td style='text-align:left']0.025 [divide] 0.005[/td]
[/tr]
[tr]
[td][/td][td]=[/td][td style='text-align:left']0.2s[/td]
[/tr]
[/table]
[/highlight]
[highlight]
[b]Example 2[/b]
[code]
Calculate the charge flowing when a current of 3 [b]amperes[/b] flows for 4 [b]seconds[/b]
[/code]
So we have:
[ul]
[li]3 amps[/li]
[li]4 seconds[/li]
[/ul]
and we need to find how much charge is flowing [b](Q)[/b].
[table]
[tr]
[td][b]Q[/b][/td][td]=[/td][td style='text-align:left'][b]I[/b] [multiply] [b]T[/b][/td]
[/tr]
[tr]
[td][/td][td]=[/td][td style='text-align:left']3 [multiply] 4[/td]
[/tr]
[tr]
[td][/td][td]=[/td][td style='text-align:left']12 coulombs[/td]
[/tr]
[/table]
[/highlight]
[highlight]
[b]Example 3[/b]
[code]
Calculate the current flowing if a charge of 6 [b]coulombs[/b] flows in 2 seconds
[/code]
So we have:
[ul]
[li]6 coulombs[/li]
[li]2 seconds[/li]
[/ul]
and we need to find how much current is flowing [b](Amps)[/b].
[table]
[tr]
[td][b]I[/b][/td][td]=[/td][td style='text-align:left'][b]Q[/b] [divide] [b]T[/b][/td]
[/tr]
[tr]
[td][/td][td]=[/td][td style='text-align:left']6 [divide] 2[/td]
[/tr]
[tr]
[td][/td][td]=[/td][td style='text-align:left']3 amps[/td]
[/tr]
[/table]
[/highlight]
