The diagram shows the path of an electron in a bubble chamber.
Which of the following can you deduce from the diagram?
(A) The electron is moving anti-clockwise.
(B) The electron is moving clockwise.
(C) The magnetic field is acting out of the page.
(D) The speed of the electron is increasing.
Source: The Student Room
In a bubble chamber, particle enters a magnetic field and a liquid which ionize. The ionization causes the path of the particle to become visible. The particle loses kinetic energy through its penetration into the liquid, the speed and the radius of the circle decreases.
Also, we could see this from the equation
mv/r = qB
Thereby, the electron is moving clockwise.