Question: Q. 2. A solenoid is connected to a battery so that a steady current flows through it. If an iron core is inserted into the solenoid, will the current increase or decrease ? Explain.
U] [SQP II 2017]
Show Answer
Solution:
Ans. On inserting the iron core, the magnetic flux linked with the solenoid will increase and an induced e.m.f. will be produced. According to Lenz’s law, the induced e.m.f. will act in a manner so as to oppose the cause, which has produced it thereby opposing an increase in magnetic flux which happens due to decrease in current.
OR
As per Lenz’s law, direction of induced emf/ current in a circuit will oppose the cause which produces it. If an iron core gets inserted in a solenoid having current, it will increase the magnetic field as a result of magnetization of iron core which increases the flux. Hence, emf induced in the coil should oppose the flux increase which induces the current in the coil in the direction opposing the increasing magnetic field by decreasing in current.
[CBSE Marking Scheme 2017]
Commonly Made Error
Students make probable errors while applying the applications of Lenz’ law in questions.
Answering Tip
- Student should remember while answering the questions that current should be marked in such a way to oppose the increase or decrease of flux.
