Question

A gas chamber is filled with hydrogen and a magnetic field is applied to it, then exposed to γ-ray. The γ-ray hits the hydrogen atom and produces high energy electron, low energy electron and positron (electron having + ve charge). The above photograph represents the trajectory of the particles. [Here magnetic field is applied Out of the plane of photo graph]

1. Which force drives the particle in a circular path and write the mathematical from.
2. Obtain a general expression for radius of the circular path.
3. Analyse the figure and match the columns given below.

Column A	Column B
1. Law energy electrons	A
2. High energy electrons	B
3. Positron	C

Answer 1

1. Magnetic Lorentz force

2. The centripetal force required for rotation is given magnetic Lorentz force Hence we can write

\(\frac{mv^2}{r}=qvB\),         \(r = \frac{mv}{qB}\)

3. Analyse the figure and match the columns given below:

• Low energy electrons – B
• High energy electron – C
• Positron – A