Discuss how the iron core changes the magnitude of induced voltage when it is inserted in a solenoid. What physical property of the iron core causes this change? Explain in the microscopic picture. What would happen if a copper core was used instead?""

Explanation:

- By putting a ferrous (iron) core inside a solenoid, the field lines are concentrated. This has the effect of strengthening the field.

- Inside the core, the field lines are much closer together → stronger field.

- The rate of change of flux increases which is proportional to induced emf.

- Iron is a particularly good core for solenoids as it is easily magnetised and demagnetised. This means that when the current is switched off the iron does not stay magnetic. Iron is said to be magnetically soft.

- The magnetism of copper is relatively poor than iron. Hence, the Magnetic flux is less than that of iron core. So rate of change of flux is also poor and so is the induced emf is small.