A uniform magnetic field $B$ and a uniform electric field $E$ act in a common region. An electron is entering this region of space. The correct arrangement for it to escape un deviated, is

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