In: Physics
E=1/2 CV^2 E= 1/2 (164 microF) (10^-6 F) (119 V)^2 E= 1.168 J How do you figure out the J from the F V^2
We begin with dimensional analysis. The formula we have is
Where F = Farads, V = Volts, and J = Joules.
Starting with J which is the unit of both Work and Energy. Work
is Force times Distance, i.e.
This gives us the units, ,
N = Newtons and L = length.
On the other side we have C and V2. Taking C first, which is given by, Capacitance = Charge divided by Voltage, i.e. , Q = fundamental unit so we can't break it down further.
For V, we have,
Where, epsilon the vacuum permittivity is given by the coulomb force,
Using this in the equation of V, we have,
Now we have what we need, so we can see what units 1/2 CV^2 will
have,