In modern physics, the concept of the photon as a quantum of light energy was introduced and explained by which scientist?

Introduction / Context:
The photon is a fundamental idea in modern physics, representing a quantum, or discrete packet, of electromagnetic energy such as light. The photon concept helped explain phenomena like the photoelectric effect, where light can eject electrons from a metal surface. This question asks which scientist introduced and used the light quantum idea to explain physical phenomena, leading to a major shift from classical wave theories of light to quantum theory.

Given Data / Assumptions:

• The subject is the photon, a quantum of light energy.
• The scientist introduced this concept to explain experimental results.
• The options list physicists and inventors from different areas of science.
• Only one of these names is strongly associated with the light quantum explanation that led to the photon concept.

Concept / Approach:
Albert Einstein is credited with introducing the light quantum idea in 1905 to explain the photoelectric effect. His work showed that light can behave as if it consists of discrete energy packets, later called photons. This helped lay the foundation for quantum mechanics and earned him the Nobel Prize in Physics. George Crum is linked to the invention of potato chips, Henry Cavendish to experiments on gases and the density of the Earth, and Humphry Davy to electrochemistry and the discovery of several elements. These figures did not introduce the photon concept, so the correct answer is Albert Einstein.

Step-by-Step Solution:
Step 1: Identify that the question is about modern physics and the quantum description of light.Step 2: Recall that Albert Einstein used the idea of light quanta to explain the photoelectric effect.Step 3: Look at the options and locate Albert Einstein as option B.Step 4: Recognise that George Crum is connected to a food invention and not to physics concepts.Step 5: Recognise that Henry Cavendish and Humphry Davy worked in chemistry and experimental physics but did not propose the photon idea.Step 6: Select Albert Einstein as the scientist who introduced the light quantum concept that became known as the photon.

Verification / Alternative check:
Textbooks on modern physics always mention Einstein 1905 paper on the photoelectric effect and describe how he treated light as if it were made of energy quanta. Later developments formalised the concept and used the term photon. None of the other individuals in the options are associated with this step in physics history. Crum, Cavendish and Davy appear in discussions of food lore, gases and chemical elements, not in the context of quantum light. This confirms that Einstein is the correct answer for exam questions on the photon concept.

Why Other Options Are Wrong:
George Crum is popularly credited with inventing potato chips, a culinary item, and has no role in quantum theory. Henry Cavendish studied gases such as hydrogen and performed experiments on gravitational attraction but did not work on quantum light. Humphry Davy discovered elements like sodium and potassium using electrolysis but is not linked to the photon model of light. Since the question is specifically about the quantum description of light, these options are not appropriate answers.

Common Pitfalls:
Some students might confuse the introduction of the photon concept with later developments in quantum mechanics and think of other physicists instead of Einstein. Others might not realise that the photon idea came from attempts to explain the photoelectric effect. To avoid confusion, remember the simple association: photon concept and photoelectric effect go with Albert Einstein, while other scientists listed contributed mainly to chemistry or everyday inventions. This clarity helps you tackle many MCQs on basic modern physics successfully.

Final Answer:
The photon concept, treating light as energy quanta, was introduced and used by Albert Einstein.