The Inductor

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The Inductor
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Inductance

• Inductance occurs when current flows through a
  (real) conductor.
• The current flowing through the conductor sets up
  a magnetic field that is proportional to the
  current.
• The voltage difference across the conductor is
  proportional to the rate of change of the
  magnetic field.

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Inductance

• The voltage difference across the inductor is
  proportional to the rate of change of the
  current.
• The proportionality constant is called the
  inductance, denoted L
• Units of Henrys (F) - V-s/A

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Inductor

The rest of the circuit
i(t)
v(t)
H
-
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Inductor Current
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Energy Stored
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Example

• The current through a 1H inductor is
• i(t) 0.45A cos(2? 60 t)
• Find v(t), p(t), and wL(t)

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Example
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Example
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Example
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Example
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Example
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Example
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Question

• What is wrong with this plot if i(t) is the
  current through an inductor?

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Reflective Exercise

• 1. Summarize the voltage/current relationships
  and the formula for energy stored for a capacitor
  and an inductor.
• 2. How are these relationships duals of each
  other?
• 3. Describe a situation in which a circuit with
  either a capacitor or an inductor has
  time-varying voltages across its elements even
  though all sources are constant.