Question

In following Figure shows a mixed source R of alpha and beta particles in a thick lead walled container. The particles pass through a magnetic field in a direction perpendicular to the plane of paper inwards as shown by ×.

1. Show in the diagram how the particles get affected.
2. Name the law used in part (a).

[Hint: Alpha particles will deflect to the left while beta particles to the right]

Answer 1

(a)

(b)

Alpha particles (α): positively charged → will be deflected to the left.

Beta particles (β): negatively charged → will be deflected to the right. 

The direction of deflection in a magnetic field is given by Fleming’s left hand rule.

• Thumb → direction of force (deflection)

• Forefinger → direction of magnetic field (into the page)

• Middle finger → direction of current or moving charge (upward).