\(\vec{F}_{E}=-e \vec{E}\)
Force on electron due to magnetic field,
\(\vec{F}_{B}=-e(\vec{v} \times \vec{B})=0\)
since \(\bar{v}\) and \(\vec{B}\) are in the same direction.
Total force on the electron,
\(\vec{F}=\vec{F}_{E}+\vec{F}_{B}=-e \vec{E}\)
Electric field opposes the motion of the electron, hence speed of the electron will decrease.
$(i)$ | $(ii)$ | $(iii)$ |
(A) $\frac{{{\mu _0}i}}{r}$ $\otimes$ | (A) $\frac{{{\mu _0}i}}{4}\left( {\frac{1}{{{r_1}}} - \frac{1}{{{r_2}}}} \right)$ $\otimes$ | (A) $\frac{{{\mu _0}i}}{4}\left( {\frac{1}{{{r_1}}} - \frac{1}{{{r_2}}}} \right)$ $\otimes$ |
(B) $\frac{{{\mu _0}i}}{{2r}}$ $\odot$ | (B) $\frac{{{\mu _0}i}}{4}\left( {\frac{1}{{{r_1}}} + \frac{1}{{{r_2}}}} \right)$ $\otimes$ | (B) $\frac{{{\mu _0}i}}{4}\left( {\frac{1}{{{r_1}}} + \frac{1}{{{r_2}}}} \right)$ $\otimes$ |
(C) $\frac{{{\mu _0}i}}{{4r}}$ $\otimes$ | (C) $\frac{{{\mu _0}i}}{4}\left( {\frac{1}{{{r_1}}} - \frac{1}{{{r_2}}}} \right)$ $\odot$ | (C)$\frac{{{\mu _0}i}}{4}\left( {\frac{1}{{{r_1}}} - \frac{1}{{{r_2}}}} \right)$ $\odot$ |
(D) $\frac{{{\mu _0}i}}{{4r}}$ $\odot$ | (D) $0$ | (D) $0$ |