Question

A wire is wound in the form of a solenoid of length $ l $ and distance $ d $ . When a strong current is passed through a solenoid, there is a tendency to

• A. increase $ l $ but decrease $ d $
• B. keep both $ l $ and d constant
• C. decrease $ l $ but increase $ d $
• D. increase both $ l $ and $ d $

Answer 1

Answer: (B)

The magnetic field produced due to a current carrying solenoid is $ B={{\mu }_{0}}ni $ It is clear that magnetic field is independent of its length and-cross-sectional area. So, when a strong current is passed through it, then both $ l $ and $ d $ remains constant.