Inductance 03 - Energy Stored in the B Field of an Inductor

SAFARI DIRECTOR: Ian

 

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OPENING QUESTIONS: There is a recurring *style* of equation for various types of energy. Comb your thoughts and see if you can suggest what that might be.

 

 

Hint:

1/2kx2, 1/2mv2

 

With that in mind, please suggest an equation for calculating the energy stored in the magnetic field of an inductor.

OBJECTIVE:  I will be able to calculate energy stored in the magnetic field of an inductor during today's class.

WORDS/FORMULAE FOR TODAY

TERMS

  • self induction/back emf
  • Inductance
  • solenoid ("A coiled wire with n loops per unit length")

CONSTANTS:

 

UNITS:

      • henry = (volt)(sec)/amps

FORMULAE:

      • UB = 1/2Li2
      • εL = L(di/dt)
      • Kirchoff Amended: ε - iR - L(di/dt) = 0
      • B = μonI
        • n = number of loops per unit length
        • I = current
      • εL = -L(di/dt) AP = -L(dI/dt)
        • dI/dt = change in current
        • L = propotionality constant depending on the "geometry of the loop and other physical characteristics"
      • L = NφB/i
        • N = number of loops (or coils if you prefer)
        • i = current that may vary with time (hence the lower case)

WORK O' THE DAY: 

Please write the full form of Kirchoff's Law (include inductance)

How many OTHER equations do we have for EMF?

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Coursework: Problem 15 and 19 on page 990
STUDY GUIDE: