Question

By inserting an iron core in a coil carrying current, the strength of its magnetic field will:
A. Increase
B. Decrease
C. Remains the same
D. Become zero

Answer 1

Hint: In this question, we need to comment on the strength of the magnetic field such that on inserting an iron coil in a current-carrying coil, the strength of the magnetic field increases, decreases, remains the same or becomes zero. For this, we will follow the property of the magnetic materials.

Complete step by step answer:When a soft iron rod also known as the core is inserted inside a solenoid then the strength of the magnetic field increases because the iron ore gets magnetized due to magnetic induction and this combination of the solenoid and the soft iron core is called an electromagnet.
This soft iron core helps to concentrate all the magnetic lines of forces through the solenoid so that the magnetic field is uniform at the cross section of the core. If the soft iron core is removed from inside, then the magnetic lines of forces start to diverge by curving sharply immediately outside the coils.
When the space between the coil and the core is reduced then a stronger magnetism is induced in the core, so to have the best electromagnets, we should tightly wound the coils around the core.
Hence we can say when an iron core is inserted in a coil carrying current, the strength of its magnetic field will increase.
Option A is correct.

Note:The strength of an electromagnet can be increased by increasing the number of loops of wire around the iron core and by increasing current or voltage.