Question

A long straight wire carries a current 10 amp. An electron travels with a velocity $5.0\times {10}^6$m/sec parallel to the wire 0.1 m away from it and in a direction opposite to the current. What force does the magnetic field of current exert on the electron?

• A. $0.8\times {10}^{-17}N$
• B. $0.8\times {10}^{-16}N$
• C. $1.6\times {10}^{-17}N$
• D. $1.6\times {10}^{-16}N$

Answer 1

The correct option is C $1.6\times {10}^{-17}N$

$B=\frac{{\mu }_0}{4\pi }.\frac{2i}{r}$

$={10}^{-7}\times \frac{2\times 10}{0.1}$

$=2\times {10}^{-5}wb/m^2$
$F=qvBsin\theta$

$=(1.6\times {10}^{-19})(5\times {10}^6)(2\times {10}^{-5})sin{90}^0$
$=1.6\times {10}^{-17}$ Newton.