# Explain how the phenomenon of self-inductance arises in a coil carrying a changing current, and explain why the self-induced EMF opposes the change in current that produces it.

> IB DP Physics Higher Level (2023 syllabus) — D.4 Induction (HL only) · Explain · 4 marks

## Mark scheme (4 marks)

1. A changing current in the coil produces a changing magnetic flux through/linking the coil itself.
2. By Faraday's law, this changing flux induces an EMF in the coil.
3. By Lenz's law, the induced EMF acts in a direction that opposes the change in flux (and hence the change in current) that caused it.
4. This opposition is consistent with conservation of energy: energy must be supplied against the back-EMF to build up (or remove) current and the associated magnetic field energy stored in the coil.

## Key terms

- [self-inductance](https://www.gradenine.co.uk/glossary/self-inductance)

## Related

- [Revision notes for IB DP Physics Higher Level (2023 syllabus)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/explain-how-the-phenomenon-of-self-inductance-b4167991) · Published by Druglandscape Ltd.