$\mathrm{B}_{\mathrm{in}}=\frac{\mu_{0}}{4 \pi} \cdot \frac{2 \mathrm{ir}}{\mathrm{R}^{2}} \quad(\mathrm{R}=$ Radius of cylinder $\mathrm{r}=$ distance of observation point from axis of cylinder)
or $\mathrm{r}=\mathrm{R}-\frac{\mathrm{R}}{4}$
Magnetic field out side the cylinder at a distance $\mathrm{r}^{\prime}$ from it's axis $\mathrm{B}_{\text {out }}=\frac{\mu_{0}}{4 \pi} \cdot \frac{2 \mathrm{i}}{\mathrm{r}^{\prime}}$
$\Rightarrow \frac{B_{\text {in }}}{B_{\text {out }}}=\frac{rr^{\prime}}{R^{2}} \Rightarrow \frac{10}{B_{\text {out }}}=\frac{\left(R-\frac{R}{4}\right)(R+4 R)}{R^{2}}$
$\Rightarrow \frac{10}{\mathrm{B}_{\mathrm{out}}}=\frac{\frac{3}{4} \mathrm{R} \times 5 \mathrm{R}}{\mathrm{R}^{2}} \Rightarrow \mathrm{B}_{\mathrm{out}}=\frac{8}{3}\, \mathrm{T}$
|
column $I$ |
column $II$ | column $III$ |
| $(I)$ Electron with $\overrightarrow{\mathrm{v}}=2 \frac{\mathrm{E}_0}{\mathrm{~B}_0} \hat{\mathrm{x}}$ | $(i)$ $\overrightarrow{\mathrm{E}}=\mathrm{E}_0^2 \hat{\mathrm{Z}}$ | $(P)$ $\overrightarrow{\mathrm{B}}=-\mathrm{B}_0 \hat{\mathrm{x}}$ |
| $(II)$ Electron with $\overrightarrow{\mathrm{v}}=\frac{\mathrm{E}_0}{\mathrm{~B}_0} \hat{\mathrm{y}}$ | $(ii)$ $\overrightarrow{\mathrm{E}}=-\mathrm{E}_0 \hat{\mathrm{y}}$ | $(Q)$ $\overrightarrow{\mathrm{B}}=\mathrm{B}_0 \hat{\mathrm{x}}$ |
| $(III)$ Proton with $\overrightarrow{\mathrm{v}}=0$ | $(iii)$ $\overrightarrow{\mathrm{E}}=-\mathrm{E}_0 \hat{\mathrm{x}}$ | $(R)$ $\overrightarrow{\mathrm{B}}=\mathrm{B}_0 \hat{\mathrm{y}}$ |
| $(IV)$ Proton with $\overrightarrow{\mathrm{v}}=2 \frac{\mathrm{E}_0}{\mathrm{~B}_0} \hat{\mathrm{x}}$ | $(iv)$ $\overrightarrow{\mathrm{E}}=\mathrm{E}_0 \hat{\mathrm{x}}$ | $(S)$ $\overrightarrow{\mathrm{B}}=\mathrm{B}_0 \hat{\mathrm{z}}$ |
($1$) In which case will the particle move in a straight line with constant velocity?
$[A] (II) (iii) (S)$ $[B] (IV) (i) (S)$ $[C] (III) (ii) (R)$ $[D] (III) (iii) (P)$
($2$) In which case will the particle describe a helical path with axis along the positive $z$ direction?
$[A] (II) (ii) (R)$ $[B] (IV) (ii) (R)$ $[C] (IV) (i) (S)$ $[D] (III) (iii)(P)$
($3$) In which case would be particle move in a straight line along the negative direction of y-axis (i.e., more along $-\hat{y}$ )?
$[A] (IV) (ii) (S)$ $[B] (III) (ii) (P)$ $[C]$ (II) (iii) $(Q)$ $[D] (III) (ii) (R)$
