The phenomenon of photoelectric emission was discovered in 1887 by

Options

A. Albert Einstein
B. Heinrich Hertz
C. Wilhelm Hallwachs
D. Philipp Lenard

Explanation

**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 electromagnetic radiation, such as visible light or gamma rays. The energy from the radiation is transferred to the electrons, allowing them to escape from the atomic structure.

2. **Historical Context**: The discovery of the photoelectric effect is significant in the field of physics as it provided evidence for the particle nature of light and contributed to the development of quantum mechanics.

3. **Identifying the Discoverer**: The question specifically asks who discovered the phenomenon of photoelectric emission in 1887. The key figure associated with this discovery is Heinrich Hertz.

4. **Hertz's Experiment**: Heinrich Hertz conducted experiments that demonstrated the photoelectric effect. He observed that an electric spark could be produced more readily when the path between two spheres was illuminated by light from another electric discharge. This was a pivotal moment in understanding the interaction between light and matter.

5. **Subsequent Contributions**: While Hertz was the first to observe this phenomenon, other scientists like Wilhelm Hallwachs, Philipp Lenard, and Albert Einstein later expanded on Hertz's work, providing deeper insights into the nature of the photoelectric effect.

**Final Answer**: The phenomenon of photoelectric emission was discovered in 1887 by Heinrich Hertz.

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