Quote

a 15H coil (inductor) carries a current of 7A. What amount of energy is stored in the magnetic field?


Need to know the Frequency applied to this Inductor, to figure Xl.
(BTW: "pi" = Greek lower case "pi", or 3.141592653589...)

Formula is: XL = 2pi FL

If F= 60Hz, then XL =:

2 * 3.141592653589 * 60 * 15.0 = 5,654 Ohms

Find Voltage: E=IR

I = 7.0 Amps,
R = 5,654 Ohms
7.0 * 5,654 = 39,578 Volts.

Find Reactive Power: VAR= E * I

E = 39,578 Volts,
I = 7.0 Amps
VARs = 277,046 VARs.

--- Personal Note:

I think the value of the Inductor is quite large - 15H.

Substituting 0.0015H (15mH) for the Inductor results in a much more reasonable Reactive Component: 277.046 VARs, with a Potential Difference of 39.578 Volts (rounded to 40 Volts).

-- Scott (EE)

---let's see if these spec. characters work now!---

Last edited by Scott35; 05/20/12 03:26 PM. Reason: Nope, symbols will not work!
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!