In the given figure, E and B are magnitudes of electric and magnetic fields which are acting on a moving electron as shown. The direction of velocity of electron is along X-axis. Then, force on electron is given by

Question

In the given figure, E and B are magnitudes of electric and magnetic fields which are acting on a moving electron as shown. The direction of velocity of electron is along X-axis. Then, force on electron is given by (A) F =q(E+v B) hat j  (B) F =q(E-v B) hat j  (C) F =q(E+v B) hat k  (D) F =q(E-v B) hat k

Tardigrade Admin · Accepted Answer

<img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/3ccfee6c93e258cae19d22ab95ffe663-.png" /> When electric and magnetic fields are perpendicular to each other. So,F E =q E =q E hat j , F B=q v × B =q( hat i × B hat k )=-q v hat j (∵ hat i × hat k =- hat j ) Therefore, force on electron is given by F =q(E-v B) hat j

Q. In the given figure, $E$ and $B$ are magnitudes of electric and magnetic fields which are acting on a moving electron as shown. The direction of velocity of electron is along $X$ -axis. Then, force on electron is given by

$F = q (E + v B) \hat{j}$

$F = q (E - v B) \hat{j}$

$F = q (E + v B) \hat{k}$

$F = q (E - v B) \hat{k}$

When electric and magnetic fields are perpendicular to each other.
So, $F_{E} = qE = qE \hat{j}, F_{B} = q v \times B$
$= q (\hat{i} \times B \hat{k}) = - q v \hat{j}$
$(∵ \hat{i} \times \hat{k} = - \hat{j})$
Therefore, force on electron is given by
$F = q (E - v B) \hat{j}$

Q. In the given figure, E and B are magnitudes of electric and magnetic fields which are acting on a moving electron as shown. The direction of velocity of electron is along X-axis. Then, force on electron is given by

F=q(E+vB)j^​

F=q(E−vB)j^​

F=q(E+vB)k^

F=q(E−vB)k^