If the circular conductor in Fig. 30-21 undergoes thermal

Chapter , Problem 1

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If the circular conductor in Fig. 30-21 undergoes thermal expansion while it is in a uniform magnetic field, a current is induced Fig. 30-21 Question 1. The SI unit of inductance is the henry (H), where 1 henry = 1 H = 1 T mZ/A. The inductance per unit length near the middle of a long solenoid of cross-sectional area A and n turns per unit length is (solenoid). (30-31) Selflnduction If a current i in a coil changes with time, an emf is induced in the coil. This self-induced emf is di '(gL = -Ldi' (30-35) The direction of '(g L is found from Lenz's law: The self-induced emf acts to oppose the change that produces it. Series RL Circuits If a constant emf '(g is introduced into a single-loop circuit containing a resistance R and an inductance L, the current rises to an equilibrium value of'(gIR according to (rise of current). (30-41) Here TL (= LlR) governs the rate of rise of the current and is called the inductive time constant of the circuit. When the source of constant emf is removed, the current decays from a value io according to (decay of current). (30-45) Magnetic Energy If an inductor L carries a current i, the inductor's magnetic field stores an energy given by (magnetic energy). (30-49) If B is the magnitude of a magnetic field at any point (in an inductor or anywhere else), the density of stored magnetic energy at that point is (magnetic energy density). (30-55) Mutuallnduction If coils 1 and 2 are near each other, a changing current in either coil can induce an emf in the other. This mutual induction is described by '(g = - M!!:.!L (30-64) Z dt and '(g = -M diz 1 dt ' (30-65) where M (measured in henries) is the mutual inductance. clockwise around it. Is the magnetic field directed into or out of the page?