An ideal solenoid of length 10 cm consists of a wire wrapped tightly around a wooden core. The magnetic field strength is $4.0 \mathrm {~T}$ inside the solenoid. If the solenoid is stretched to $25 \mathrm {~cm}$ by applying a force to it, what does the magnetic field become?
A)1.6 T
B)10.0 T
C)20 T
D)4.0 T

Question

Quizplus · Accepted Answer

The magnetic field inside an ideal solenoid is given by $ B = \mu_0 n I $, where $ n $ is the number of turns per unit length. When the solenoid is stretched, the number of turns per unit length decreases, reducing the magnetic field strength proportionally. Since the length increases from 10 cm to 25 cm, the field strength decreases by a factor of 2.5, resulting in a new field strength of $ 4.0 \, \text{T} / 2.5 = 1.6 \, \text{T} $.

An Ideal Solenoid of Length 10 Cm Consists of a Wire