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.