Question

For each of the situations below, a charged particle enters a region of uniform magnetic field. Determine the direction of the force on each charge due to the magnetic field.

Determine the direction of the force on the charge due to the magnetic field.

points into the page.  points out of the page.  points neither into nor out of the page and.

Determine the direction of the force on the charge due to the magnetic field.

points out of the page.  points into the page. points neither into nor out of the page and.

Determine the direction of the force on the charge due to the magnetic field. Note that the charge is negative.

points out of the page.  points into the page.  points neither into nor out of the page and.

Answer 1

Part A

Consider the expression for the force acting on a charged particle,

$$ F=B q v \sin \theta $$

Consider the first case, \(\theta=180^{\circ}\)

Hence magnetic force acting,

$$ \begin{aligned} F &=B q v \sin 180^{\circ} \\ &=0 \end{aligned} $$

That is, the magnetic force acting is zero in this case.

Part B

Consider the figure; the direction of velocity is acting upwards. Applying the Fleming's left hand rule. The magnetic force is acting towards right. That is magnetic force points into the page.

Part \(\underline{\mathrm{C}}\)

Here the particle is negatively charged. The direction of magnetic force acting on a negatively charged particle is just opposite to that acting on a positively charged particle. So the direction is into the page.