Question

In Rutherford’s experiment, generally the thin foil of heavy atoms, like gold, platinum etc. have been used to be bombarded by the α-particles. If the thin foil of light atoms like aluminium etc. is used, what difference would be observed from the above results ?

Answer 1

Concept Used:

In Rutherford’s scattering experiment, the extent of deflection of α-particles depends on the magnitude of positive charge and mass of the nucleus.

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Observation with heavy metal foil:

Heavy atoms like gold or platinum have a large nuclear charge and mass. Hence:

• Most α-particles pass straight through
• Some are deflected through small angles
• A very few are deflected through large angles or rebound

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Effect of using light atoms (e.g., aluminium):

Light atoms have smaller nuclear charge and mass. Therefore:

• Electrostatic repulsion between α-particles and nucleus is much weaker
• Probability of large-angle scattering is extremely low
• Almost no α-particles are reflected back

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Resulting Difference:

When a thin foil of light atoms is used, most α-particles pass through the foil with little or no deflection, and large-angle scattering is rarely observed.

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Final Answer:

Using a foil of light elements results in very small deflections of α-particles, and the characteristic large-angle scattering observed with heavy metal foils is almost absent.