Bohr's basic idea of discrete energy levels in atoms and the process of emission of photons from the higher levels to lower levels was experimentally confirmed by experiments performed by

Options

A. Michelson- morley
B. millikan
C. joule
D. franck and hertz

Explanation

To answer the question regarding who experimentally confirmed Bohr's basic idea of discrete energy levels in atoms and the emission of photons from higher levels to lower levels, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Bohr's Model**:
- Bohr proposed that electrons orbit the nucleus in specific, quantized energy levels. The angular momentum of these orbits is quantized and is given by the formula \( L = n \frac{h}{2\pi} \), where \( n \) is an integer (1, 2, 3,...), and \( h \) is Planck's constant.

2. **Energy Levels**:
- The energy associated with these levels is also discrete. The energy of an electron in a particular orbit can be calculated using the formula:
\[ E_n = -\frac{k e^4 m}{2 \hbar^2 n^2} \]
where \( k \) is Coulomb's constant, \( e \) is the charge of the electron, \( m \) is the mass of the electron, and \( \hbar \) is the reduced Planck's constant.

3. **Photon Emission**:
- When an electron transitions from a higher energy level (E2) to a lower energy level (E1), it emits a photon. The energy of the emitted photon corresponds to the difference in energy between the two levels:
\[ \Delta E = E_2 - E_1 \]
- This process is a fundamental aspect of atomic physics and is responsible for the spectral lines observed in atomic spectra.

4. **Experimental Confirmation**:
- The experimental confirmation of Bohr's ideas was achieved by scientists Frank and Hertz. They conducted experiments that demonstrated the quantized nature of energy levels in atoms. Their work involved bombarding mercury atoms with electrons and observing the resulting energy transitions.

5. **Conclusion**:
- Therefore, the correct answer to the question is that Bohr's ideas were experimentally confirmed by the experiments performed by Frank and Hertz.

### Final Answer:
Bohr's basic idea of discrete energy levels in atoms and the process of emission of photons from higher levels to lower levels was experimentally confirmed by Frank and Hertz.

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