Question

Which of the following observations were obtained from $\alpha$-particle scattering experiment?

• A. Most of the fast moving $\alpha$-particles passed straight through the gold foil
• B. Some of the $\alpha$-particles were deflected by the foil by small angles
• C. One out of every 12000 particles appeared to rebound
• D. All of the above

Answer 1

Answer: (D)

All of the above

Ernest Rutherford performed an experiment to know the arrangement of electrons within an atom. In this experiment, fast-moving alpha particles were made to fall on a thin gold foil (100 nm thickness). The $\alpha$-particles are doubly charged helium ions. It was expected that $\alpha$-particles would be deflected by subatomic particles in the gold atom. Since $\alpha$-particles were much heavier than protons, he did not expect to see large deflections.

But, the $\alpha$-particle scattering experiment gave totally unexpected results.
The following observations were made:
(i) Most of the fast-moving -particles passed straight through the gold foil.
(ii) Some of the -particles were deflected by the foil by small angles.
(iii) Surprisingly one out of every 12000 particles appeared to rebound.