Question

Choose the right answer from the following. A constant current $I$ is maintained in a solenoid. Which of the following quantities will not increase if an iron rod is inserted in the solenoid along its axis?
(a) The magnetic field at the centre
(b) Self-inductance of the solenoid
(c) Magnetic flux linked with the solenoid
(d) Rate of Joule heating.

Answer 1

A solenoid is a device that consists of a wire coil, a casing, and a movable plunger (armature). When an electrical current is applied to the coil, a magnetic field arises around it, pulling the plunger in. A solenoid, to put it another way, turns electrical energy into mechanical work.

Complete step-by-step solution:
The permeability of the medium between the solenoid will rise if an iron rod is added, as the relative permeability of iron is greater than one. As a result, the magnetic field will grow. The magnetic flux associated grows as the magnetic field increases. The inductance will grow as the flux linkage increases.
Only the current and the resistance affect joule heating. Insertion of an iron rod has no influence on the solenoid's current or resistance. As a result, joule heating will be unaffected.
In other words we can also say that due to the high magnetic permeability of iron, when an iron rod is put within a solenoid, the magnetic field inside the solenoid increases. The magnetic flux increases as the magnetic field increases. The solenoid's self-inductance rises as well, because the coil's self-inductance $\left( L \right)$ is proportional to the permeability of the material inside the solenoid. The rate of joule heating remains constant.

Note: A solenoid is a wire coil that is used in electromagnets, inductors, antennas, valves, and other devices. Medical, locking systems, industrial use, the bottom line, and Automotive Solenoid Applications are just a few examples of solenoid applications.