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?
- the magnetic field at the centre
- self-inductance of the solenoid
- magnetic flux linked with the solenoid
- rate of Joule heating.
Answer: rate of joule heating
Explanation: When an iron rod is inserted inside a solenoid the magnetic field inside the solenoid increases due to the high magnetic permeability of iron. Due to the increased magnetic field, the magnetic flux also increases. The self-inductance of the solenoid also increases because self-inductance (L) of the coil is directly proportional to the permeability of the material inside the solenoid. The rate of joule heating doesn’t change.
