Following figure shows the path of an electron that passes through two regions, containing uniform magnetic fields of magnitudes $B_1$ and $B_2$. Its path in each region is a half circle. Choose the correct option.

A particle with charge $q$, moving with a momentum $p$ enters a uniform magnetic field normally. The magnetic field has magnitude $B$ and is confined to a region of width $d$, where $d<\frac{p}{Bq},$ The particle is deflected by an angle $\theta$ in crossing the field

A particle having a charge of $10.0 \mathrm{\mu C}$ and mass $1 \mathrm{\mu g}$ moves in a circle of radius $10 \mathrm{cm}$ under the influence of a magnetic field of induction $0.1 \mathrm{T}$. When the particle is at a point $P$, a uniform electric field is switched on so that the particle starts moving along the tangent with a uniform velocity. The electric field is 

In the below figure, an electron of mass $m$, charge $-e$, and low (negligible) speed, enters the region between two plates of potential difference $V$ and plate separation $d$, initially headed directly towards the top plate. A uniform magnetic field of magnitude $B$ is normal to the plane of the figure. Find the minimum value of $B$, such that the electron will not strike the top plate.

Bainbridge’s mass spectrometer separates ions having the same velocity. The ions, after entering through slits, $S_1\mathrm{and} S_2$, pass through a velocity selector composed of an electric field produced by the charged plates $P$ and $P\text{'}$ and a magnetic field $\overrightarrow{\mathit{B}}$ perpendicular to the electric field and the ion path. Ions that then pass undeviated through the crossed $\overrightarrow{\mathit{E}}\mathit{ }\mathrm{and} \overrightarrow{\mathit{B}}$  field enter into a region where a second magnetic field $\overrightarrow{B}\text{'}$ exists, where they are made to follow circular paths. A photographic plate (or a modern detector) registers their arrival. If $r$ is the radius of the circular orbit, then specific charge $\frac{\mathit{q}}{\mathit{m}}$ of ion is 

Two charged particles$M$ and $N$ enter a space of uniform magnetic field with velocities perpendicular to the magnetic field. The paths are as shown in the figure. The possible reason for different paths may be