An electron e-m is projected along positive y- axis with velocity v0 in a region- which has electric field E0 - and magnetic field B0 - After how long will the electron passes through the point of projection-

Given that B=B_0 ( ĵ); E=E_0 ĵ; electron is moving in +ve y direction, ∴v=v_0 ĵ Here, B||v, so magnetic force will be zero. ∴ F_m=qvBsin 0^∘= 0 And electr ...

You visited us 1 times! Enjoying our articles? Unlock Full Access!

Byju's Answer

Standard XII

Physics

Electric Field

An electron e...

Question

An electron $(e, m)$ is projected along positive $y -$ axis with velocity $v_{0}$ in a region, which has electric field $E_{0}^j$ and magnetic field $B_{0} (-^j)$ . After how long will the electron passes through the point of projection.

\frac{2 m v_{0}}{e E_{0}}

No worries! We‘ve got your back. Try BYJU‘S free classes today!

\frac{2 m v_{0}}{e E_{0}}

No worries! We‘ve got your back. Try BYJU‘S free classes today!

\frac{2 m v_{0}}{e E_{0}}

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

\infty

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is C $\frac{2 m v_{0}}{e E_{0}}$
Given that
$\to B = B_{0} (-^j); \to E = E_{0}^j;$

electron is moving in $+ v e y -$ direction,

$∴ \to v = v_{0}^j$

Here, $\to B | | \to v$ , so magnetic force will be zero.

$∴ F_{m} = q v B sin 0^{\circ} = 0$

And electric force will be

$_{e} = q \to E = (- e) E_{0}^j$

$∴ a_{y} = \frac{- e E_{0}}{m}^j$

Since, velocity and acceleration have opposite direction, so electron will pass to point of projection after some time.

Now apply equation of motion in $y -$ direction,

$y = u_{y} t + \frac{1}{2} a_{y} t^{2}$

Assuming after time $t$ , it will pass through the point of projection. So,

$y = 0; a_{y} = \frac{- e E_{0}}{m}; u_{y} = v_{0}$

$\Rightarrow 0 = v_{0} t + \frac{1}{2} (\frac{- e E_{0}}{m}) t^{2}$

$∴ t = \frac{2 m v_{0}}{e E_{0}}$

Hence, option $(c)$ is correct.

Suggest Corrections

Similar questions

Q. An electron projected with velocity

- v

v_{0}

\land i

in the electric field

E = {¯ ¯¯ ¯ E}_{0}^j

. Trace the path followed by the electron

E_{0}

Q. A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected in the region such that its velocity is pointed along the direction of fields, then the electron

A magnetic field

\to B = B_{0}^j

exists in the region

a < x < 2 a

and

\to B = - B_{0}^j

in the region

2 a < x < 3 a

, where

B_{0}

is a positive constant. A positive point charge moving with a velocity

\to v = v_{0}^i

where

v_{0}

is a positive constant, enters the magnetic field at

x = a

. The trajectory of the charge in this region can be like,

Q. A uniform electric field and a uniform magnetic field exist in a region in the same direction. An electron is projected with velocity pointed in the same direction the electron will

Q. A uniform electric field and a uniform magnetic field acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity, then.

Join BYJU'S Learning Program

Explore more

Electric Field

Standard XII Physics

Join BYJU'S Learning Program

An electron (e,m) is projected along positive y− axis with velocity v0 in a region, which has electric field E0 ^j and magnetic field B0 (−^j). After how long will the electron passes through the point of projection.

An electron $(e, m)$ is projected along positive $y -$ axis with velocity $v_{0}$ in a region, which has electric field $E_{0}^j$ and magnetic field $B_{0} (-^j)$ . After how long will the electron passes through the point of projection.