## 16 Questions

What are the two major breakthroughs of modern physics?

Relativity and Quantum Mechanics

What is the foundation of principles in Quantum Mechanics?

Purely probabilistic in nature

Who proposed the Quantum theory to explain Blackbody radiation?

Max Planck

What did Louis de-Broglie propose about matter?

Matter possesses wave as well as particle characteristics

What does Classical Mechanics describe?

The motion of macroscopic objects

What is the mass–energy relationship proposed by Einstein?

𝐸= 𝑚𝑐 2

What is the name of the law that states the peak of wavelength at which the maximum emission occurs for any given temperature is inversely proportional to the absolute temperature of the body?

Wien’s displacement law

What is the relationship between the intensity of radiation and the wavelength at a given temperature?

The intensity of the radiation increases with an increase in wavelength till it reaches its maximum, then reduces with an increase in wavelength.

What is the term used for a body that absorbs all radiation incident upon it regardless of the frequency of radiation?

Black body

What is the equation for the energy of radiation emitted from a black body at a temperature T?

E = σT^4

What are the three failures of Classical Physics mentioned in the text?

- Black Body Radiation 2. Structure of an Atom 3. Photoelectric effect

According to Wien’s Displacement Law, how is the peak of wavelength related to the absolute temperature of the body?

The peak of wavelength is inversely proportional to the absolute temperature of the body.

What is the relationship between the wavelength and the temperature as per Wien’s Displacement Law?

With an increase in temperature, the wavelength decreases.

What is the relationship between the energy and the temperature in the equation for the energy of radiation emitted from a black body?

The energy is proportional to the fourth power of the temperature.

What is the name of the constant in the equation for the energy of radiation emitted from a black body?

Stefan’s constant

What is the ability of a black body related to its ability to emit radiation?

The ability of the body to radiate is closely related to the ability to absorb the radiation.

## Study Notes

- Modern physics is a field of physics that emerged in the early 20th century, built on the principles of Relativity and Quantum Mechanics.
- Classical Mechanics, the predecessor of modern physics, is based on the measurement of macroscopic objects' properties such as position, mass, velocity, and acceleration.
- Quantum Mechanics, however, is a new field that deals with the behavior of matter and energy at the atomic and subatomic level.
- In Quantum Mechanics, the position and momentum of a particle cannot be measured simultaneously due to its probabilistic nature.
- The foundation of Quantum Mechanics was laid with the proposal of the Quantum theory by Max Planck to explain Blackbody radiation, the Photo-Electric Effect, and the dual nature of matter and radiation.
- Classical Physics, which describes the motion of macroscopic objects, failed to explain the behavior of matter at the microscopic level, leading to the development of Quantum Mechanics.
- The failures of Classical Physics include the inability to explain Blackbody Radiation, the structure of the Atom, and the Photoelectric Effect.
- Blackbody Radiation is the energy emitted from a perfect absorber, which absorbs all the incident radiation regardless of frequency.
- The energy distribution of Blackbody Radiation is not uniform throughout the spectrum and follows a specific pattern.
- The peak wavelength of emission, which occurs at the maximum intensity, decreases as the temperature increases, as stated in Wien's Displacement Law.
- The total energy emitted at a given temperature can be calculated by the area under the curve of the spectral distribution.
- The Rayleigh-Jeans explanation of the origin of Blackbody Radiation involved the reflection of radiation back and forth in a cavity, forming a system of standing waves.

Test your knowledge of modern physics, which is a branch of physics that developed in the early 20th century, based on the two major breakthroughs of relativity and quantum mechanics. This quiz covers classical mechanics, quantum mechanics, and their applications in the modern understanding of the physical world.

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