Beams of charged particles are deflected by an electric field. In identical conditions the angle of

deflection of a particle is proportional to its charge / mass ratio.

In an experiment, protons are deflected by an angle of + 15°. In another experiment under

identical conditions, particle Y is deflected by an angle of - 5°.

What could be the composition of particle Y?

protons neutrons electrons

1) 1 2 2

2) 3 3 5

3) 4 5 1

Correct Answer: Option B: 3 protons, 3 neutrons and 5 electrons

Reason:

Since, particle 'Y' deflected at an angle (-5°) opposite to that of proton ( + 15°), this suggest that particle 'Y' has charge opposite to the of proton. In option B, there are 3 protons and 5 electrons. Thus, net charge is - 2.

Also, magnitude of deflection of 'Y' particles is less as compared to protons, this signifies that, it is very heavy as compared to protons. Both of this criteria is satisfied by option B. Hence, it is correct choice.