Energy of the beam of `alpha`-particles used by Geiger and Marsden in scattering experiment is

Options

A. 2.2 MeV
B. 4.2 MeV
C. 5.1 MeV
D. 5.5 MeV

Answer

To solve the question regarding the energy of the beam of alpha particles used by Geiger and Marsden in their scattering experiment, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Experiment**: The experiment conducted by Geiger and Marsden, under the guidance of Rutherford, involved the scattering of alpha particles off a thin gold foil. This experiment was crucial in leading to the discovery of the atomic nucleus.

2. **Identifying the Source of Alpha Particles**: In the experiment, a source of radioactive material was used to emit alpha particles. These particles are positively charged and are composed of two protons and two neutrons.

3. **Energy of Alpha Particles**: The energy of the alpha particles used in the experiment is a key detail. According to historical records, the energy of the alpha particles emitted from the radioactive source was approximately 5.5 MeV (mega electron volts).

4. **Analyzing the Options**: Given the options provided in the question, we need to identify which one corresponds to the energy of the alpha particles. The correct energy value is 5.5 MeV.

5. **Conclusion**: Therefore, the energy of the beam of alpha particles used by Geiger and Marsden in their scattering experiment is **5.5 MeV**.

### Final Answer:
The energy of the beam of alpha particles used by Geiger and Marsden in the scattering experiment is **5.5 MeV**.

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