Question

A long solenoid is formed by winding 20 turns/cm. What will be the current necessity to produce a magnetic field of 20 millitesla inside the solenoid
($\frac{{\mu }_0}{4\pi }={10}^{-7}$ meter/ampere)

• A. 8.0 A
• B. 4.0 A
• C. 2.0 A
• D. 1.0 A

Answer 1

The correct option is A 8.0 A

$\text{Given}:$ n=20, B=20mT=20$\times {10}^{-3}T$

$\text{Solution}:$

We know, the magnetic field inside the solenoid is given by,

$B={\mu }_{0}ni$

$\therefore 20\times {10}^{-3}=4\pi \times {10}^{-7}\times 20\times {10}^2\times i$

Hence,

i=8⋅0A.

$\text{Hence A is the correct option}$