Question

A solenoid of length $0.5\text{m}$ has a radius of $1\text{cm}$ and is made up of $500$ turns. It carries a current of $5\text{A}$. The magnitude of magnetic field inside the solenoid is

• A. $3.14\times {10}^{-3}\text{A}$
• B. $6.28\times {10}^{-3}\text{A}$
• C. $9.42\times {10}^{-3}\text{A}$
• D. $9.42\times {10}^{-4}\text{T}$

Answer 1

The correct option is B $6.28\times {10}^{-3}\text{A}$

Given,

$N=500,l=0.5\text{m},I=5\text{A}r=1\text{cm}={10}^{-2}\text{m}$

Field inside the long solenoid is,

$$B=\frac{{\mu }_{0}NI}{l}={\mu }_{0}nI$$

$=\frac{4\pi \times {10}^{-7}\times 500\times 5}{0.5}$

$=6.28\times {10}^{-3}\text{T}$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, (b) is the correct answer.