Electronics > Beginners
V*C = I*t
bostonman:
Someone used this formula and I don't understand how the units equal.
V*C = I*t
The SI units (from what I found are):
Volt = kg·m2·s−3·A−1
Coulomb = A * s
I = A
t = s
What am I missing in the SI units that is not allowing both sides to equal each other?
T3sl4co1l:
kg.m^2/s^3 == W == V.A ;)
Handy to remember that capacitance is F == s/Ω, and inductance is H == Ω.S. :)
Tim
ebastler:
The “C” in your formula does not stand for Coulomb (which is a unit), but for capacity (which is a quantity, and its unit is Coulomb/Volt).
The „V“ stands for voltage, but its unit happens to be Volt, so that part is ok. :-)
TimFox:
Incidentally, when writing equations carefully, one should put the variable "voltage" V in italics, and the unit "volts" V in roman. Similarly, italic C is the variable "capacitance" and roman C is the unit "coulombs".
Nominal Animal:
Dimensional analysis, my favourite!
I like to write the units in angle brackets, thus:
V [ V ] · C [ C / V ] = I [ A ] · t [ s ]
For dimensional analysis, just write the units:
[ V ] · [ C / V ] = [ A ] · [ s ]
which is equivalent to
[ C ] = [ A s ]
which is true, 1 C = 1 A s.
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