Gujarat BoardEnglish MediumSTD 12 SciencePhysicsELECTROMAGNETIC INDUCTION2 Marks
Question
What is self induction ? Obtain expression for self induced emf.
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Answer
→When electric current through an isolated conducting coil is changed, magnetic flux linked with it changes. As a result, induced emf is produced in the coil. This phenomenon is called self induction. →Here, induced emf is called self induced emf. →Suppose, electric current passing through an isolated coil having N turns is I . →Total magnetic flux linked with coil, $\begin{array}{c} N \phi_{ B } \propto I \\ \therefore \quad N \phi_{ B }= L I \end{array}$ →Proportionality constant L in equation (1) is called self inductance. →On changing current with time, magnetic flux linked changes. As a result, induced emf is produced. $\therefore N \frac{d \phi_{ B }}{d t}= L \frac{d I }{d t}$ →According to Faraday's law, $\varepsilon=- N \frac{d \phi_{ B }}{d t}$ From equation (2) and (3), $\varepsilon=- L \frac{d I }{d t}$ Equation (4) is expression for self induced emf.
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