By photoelectric effect, Einstein, proved

Options

A. E = hV
B. `KE = (1)/(2) mv^(2)`
C. `E = mc^(2)`
D. `E = (Rhc^(2))//(n^(2))`

Answer

To solve the question regarding what Einstein proved through the photoelectric effect, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Photoelectric Effect**:
The photoelectric effect refers to the phenomenon where electrons are emitted from a material (usually a metal) when it is exposed to light of sufficient frequency.

2. **Wave vs. Particle Theory**:
Classical wave theory of light could not explain the photoelectric effect. For instance, it could not account for the observation that light below a certain frequency, regardless of its intensity, does not cause electron emission.

3. **Einstein's Hypothesis**:
In 1905, Albert Einstein proposed that light is composed of particles called photons. Each photon has energy that is directly proportional to its frequency. This means that the energy (E) of a photon can be expressed as:
\[ E = h \nu \]
where \( h \) is Planck's constant and \( \nu \) (nu) is the frequency of the light.

4. **Collision of Photons with Electrons**:
When light (as photons) strikes the surface of a metal, the photons collide with electrons in the metal. If the energy of the incoming photons is greater than the work function (the minimum energy needed to remove an electron from the metal), electrons are ejected from the surface.

5. **Conclusion**:
Therefore, through the photoelectric effect, Einstein proved that light behaves as a stream of particles (photons) and that the energy of these photons is quantized, leading to the conclusion that light has both wave-like and particle-like properties (wave-particle duality).

### Final Answer:
By the photoelectric effect, Einstein proved that light consists of particles called photons, and the energy of these photons is given by the equation \( E = h \nu \).

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