Consider a solenoid of length L,N windings,and radius b (L is much longer than b).A current I is flowing through the wire.If the length of the solenoid became twice as long (2L),and all other quantities remained the same,the magnetic field inside the solenoid would
A) remain the same.
B) become twice as strong.
C) become one half as strong.

Question

Quizplus · Accepted Answer

The magnetic field inside the solenoid is given by B = μ₀NI/L, where μ₀ is the permeability of free space. If the length of the solenoid is doubled but the number of windings and current remain the same, then the new magnetic field would be B' = μ₀NI/2L. We can see that B' is one-half of the original field B. Therefore, the correct choice is C.

Consider a Solenoid of Length L,N Windings,and Radius B (L