What experimental discovery led niels bohr to revise rutherford’s model of the atom ?

The experimental discoveries that led Niels Bohr to propose an improved model of the atom were the line spectrum or emission spectrum of hydrogen and the photoelectric effect.

Explanation:

There are several types of electromagnetic radiation. Going from long-wavelength, low-frequency radio waves to short-wavelength, high-frequency gamma rays. This range of frequencies and wavelengths is known as the electromagnetic spectrum. Only a small part of this spectrum can be seen with the naked eye. Thus it is called the visible region of the spectrum.

If the white light is passed through a glass prism, it is possible to see that visible region as a "rainbow" of colors. But if we use a hydrogen lamp instead of an ordinary white light lamp, a discontinuous spectrum will appear. This is a group of narrow colored lines separated by dark regions. Each line corresponds to electromagnetic radiation of a specific frequency and wavelength. This emission spectrum or line spectrum is characteristic of hydrogen and, therefore, can be used to identify it.

On the other hand, Albert Einstein used the Planck's Quantum theory to explain the photoelectric effect, which consists of a beam of electrons produced when a beam of light collides with certain surfaces. This effect could not be explained by classical physics.

Einstein said that the electromagnetic radiation is quantized; it means that light and all the other electromagnetic radiations are made of little packets of energy, known as photons.

Niels Bohr tried to combine ideas from classical physics and the quantum theory to explain the line spectrum of hydrogen atom and its structure. That  was the moment when he realized that electrons could not have chaotic movement around the nucleus but with specified energy values or energy levels.