Question

An ideal solenoid carries a current 4 A. Number of turns per unit length is 1500. An electron is projected in solenoid along direction perpendicular to axis, find frequency of electron in $rev/s$.

• A. $4.5\times {10}^6$
• B. $6\times {10}^8$
• C. $2\times {10}^8$
• D. $3\times {10}^8$

Answer 1

The correct option is C $2\times {10}^8$

$B=\mu nir=\frac{mV}{qB}T=\frac{2\pi m}{qB}n=\frac{1}{T}=\frac{qB}{2\pi m}=\frac{q\mu ni}{2\pi m}$

Putting values of respective variables and constants, we get $n=2\times {10}^{8}rev/s$