An electron travelling with a speed along the positive -axis enters into a region of magnetic field where It comes out of the region with speed then [2004]

Question

An electron travelling with a speed $u$ along the positive $x$ -axis enters into a region of magnetic field where $B = - B_{0} \hat{k}$ $(x > 0) .$ It comes out of the region with speed $v$ then [2004]

Smart Achievers · Accepted Answer

(2)

Magnetic force on the charged particle does not change its speed.

$∴$ $u = v$

The force acting on the electron will be perpendicular to the direction of velocity till the electron remains in the magnetic field. Therefore, the electron will follow the path as given below.

Hence, the electron comes out with speed $v = u$ and at $y < 0$ .

Solution

Q.
An electron travelling with a speed $u$ along the positive $x$ -axis enters into a region of magnetic field where $B = - B_{0} \hat{k}$ $(x > 0) .$ It comes out of the region with speed $v$ then [2004]

1 $v = u$ at $y > 0$

2 $v = u$ at $y < 0$

3 $v > u$ at $y > 0$

4 $v > u$ at $y < 0$

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Solution

Q. An electron travelling with a speed u along the positive x-axis enters into a region of magnetic field where B=-B0k^ (x>0). It comes out of the region with speed v then [2004]

1 v=u at y>0

2 v=u at y<0

3 v>u at y>0