Question

In the beginning of the 20th century, the matter wave concept was introduced by:

• A. Broglie
• B. Avogadro
• C. Heisenberg
• D. Einstein

Hint:

De Broglie’s hypothesis led to the development of wave-particle duality, which was fundamental in the study of quantum mechanics.

Answer 1

The Correct Option is A

Step 1: Concept.
The relation wavelength equals h divided by momentum connects a particle's momentum to an associated wavelength, which is the mathematical statement of the matter wave idea.

Step 2: Match the name.
This equation and the idea behind it are credited to Louis de Broglie, and are separate from Avogadro's gas law, Heisenberg's uncertainty relation, or Einstein's photoelectric equation.

Step 3: Final Answer.
The matter wave concept was introduced by Broglie.

Answer 2

Placing each scientist's key idea on a rough timeline of early 20th century physics also narrows this down.

1. Avogadro: Avogadro's hypothesis dates from 1811, well before the era the question refers to, and it is about gas volumes, not waves or particles, so it is out on both timing and topic.
2. Einstein: Einstein's photoelectric effect paper came in 1905, early in the correct era, but it explains light, already known as a wave, behaving like particles, the reverse of proposing that matter behaves like waves.
3. Broglie: In 1924, right in the early 20th century window the question refers to, de Broglie proposed that particles of matter, such as electrons, should also show wave behaviour, introducing the matter wave concept for the first time.
4. Heisenberg: Heisenberg's uncertainty principle came later, in 1927, and it addresses the limits of measuring position and momentum together, not the wave nature of matter itself.

Among these, only de Broglie's 1924 proposal specifically introduces the idea that matter particles carry wave properties.

So the correct answer is Broglie.