Question

In the Geiger-Marsden experiment, the force that scatters particles is
A. nuclear force
B. coulomb force
C. both A and B
D. gravitational force

Answer 1

Hint: For the solution we will discuss the Geiger-Marsden experiment or the Rutherford gold foil experiment as it is more commonly known and how it was carried out. Then, we will discuss its result and the conclusions drawn from it and finally using the conclusion and the results we will figure out the force acting on the particle.

Complete answer:
The Geiger-Marsden experiment or as it is more commonly known, Rutherford gold foil experiment. Here, a thin gold foil was bombarded with alpha particles and the scattering of particles was observed. Alpha particles are the nucleus of a Helium atom and thus, have a positive charge and are very small in size. The observations were that almost all particles crossed unaffected. A few of them deflected slightly and 1 in 20000 particles were deflected back perfectly. From this the conclusions drawn were that most of the space inside the atom is empty as most of the particles can freely pass through the foil without deflections, and the positive charge is confined in a very small region. From this we conclude that the particles were deflected due to force from the nucleus when they come close to the nucleus as both are positively charged and the force will be the electrostatic force or the coulomb force. Hence, the correct option is B, i.e. coulomb force.

So, the correct answer is “Option B”.

Note:
If the particles have high enough velocity and pass the nucleus at a very close distance, they will deflect due to both coulomb and nuclear force. However, particles with such high energy are not used in this experiment so the only force for deflection of the particles is the coulomb force. The gravitational force always acts on the particles but it does not cause the deflections in this case.