Class 4 (4th Engineer) MET 📅 May 2023

Exam Question

(a) What is self induction? (6)

(b) A coil of 800 turns is wound on a wooden former and a current of 5A is passed through it to produce a magnetic flux of 200 micro-webers. Calculate the average value of e.m.f. induced in the coil when the current is (i) switched off in 0.08 seconds (ii) reversed in 0.2 seconds.

Reference Answer

### (a) Self-Induction
Self-induction is a fundamental electromagnetic phenomenon where a changing current in an electrical circuit or coil induces an electromotive force (EMF) within the **same** circuit or coil. This induced EMF is often referred to as a "back EMF" because, according to Lenz's Law, it always opposes the change in current that produced it.
#### Detailed Explanation:
* **Principle of Operation:**

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