Modern Physics

Modern Physics

​Special Relativity

​The mechanics of objects moving at high velocities, near the speed of light, in contrast to Newtonian mechanics, which deals with velocities found in daily life. Einstein is quoted as saying, “Common sense is that layer of prejudice laid down prior to the age of sixteen.”

​

This remark was prompted by the realization that the laws of special relativity are contrary to our common sense because we do not travel at speeds near the speed of light.

​General relativity

​Treats gravitational fields as equivalent to acceleration. The theory relates to the physics of the stars and even to the evolution of the universe—cosmology

​Frames of reference

​Newton’s laws apply in any nonaccelerating frame of reference, called an inertial frame, that is, one with constant velocity. According to Newtonian physics, if the laws of mechanics are valid in one inertial frame of reference, they must be valid in any inertial frame of reference.

​The person at the station may say that he is at rest while the train moves past in one direction; the person on the train may say that she is at rest and that the station is moving past in the opposite direction. As long as the frame of reference is nonaccelerating, there is no way to prove that any given frame of reference is absolutely at rest, nor is there a preferred frame of reference.

​The special theory of relativity

​Einstein suggested that absolute motion has no meaning, that all motion is relative. He formulated two basic postulates for the special theory of relativity.

• The laws of physics are the same in all inertial reference frames.

• The speed of light is the same regardless of the frame of reference of the observer.

These simple postulates led to profoundly different ways of viewing the universe.

Multiple Choice

Mass energy relation is

• E=mc2

• E=T+V

• E=T-V

• M=Ec2

Multiple Choice

On a train travelling at 0.6c, an observer sitting in the middle of a train carriage sees 2 lights at each end of the carriage turn on simultaneously. What would an observer on the platform see?

• Both lights turn on simultaneously

• The front light turn on first

• The rear light turn on first

• The lights flash

Multiple Choice

What is the formula for special relativity?

• $$E=MC^2$$

• $$E=MS^2$$

• $$C=ME^2$$

• $$M=EC^2$$

Multiple Choice

1.If you were in spaceship traveling at the speed close to the speed of light (with respect to the earth) you would notice that___________

• your pulse rate is different than normal

• your mass is different than normal

• some of your physical dimensions were smaller than the normal

• none of these effects occur

Multiple Choice

The speed of light (c) =

• 3 x 10⁸ miles/hour
• 3 x 10⁸ meters/second
• 3 x 10⁸ kilometers/hour
• none of these

Multiple Choice

The special theory of relativity was derived by:

• Galileo
• Newton
• Einstein
• Sitter

Multiple Choice

A postulate is something that is accepted as true at the beginning of a logical article.

• True
• False

Multiple Choice

The speed of light is constant in all frames of reference.

• True
• False

Multiple Choice

Which of the following is not a consequence of special relativity?

• Moving objects appear shorter in length (thinner) than stationary objects.
• Time appears to move at a different rate for objects moving relative to each other.
• Mass and energy are the same thing: if you increase an object’s energy, you also increase its mass.
• Nothing is certain; everything is relative.

Multiple Choice

When you approach a light source, the light from that source has a speed 

• greater than c. 
• less than c. 
• equal to c.
  

Multiple Choice

Based on the concepts of Special Relativity time travel is...

• not possible

• possible only in the ability to travel into the past.

• possible only in the ability to travel to the future.

• possible to travel either forward or backward in time.

​Lorentz Contraction

​The Lorentz contraction is the effect that an observer moving with an object of a given length will find the object to be shortened compared to an observer at rest relative to this motion. (Note that this shortening occurs only in the direction of motion.) Again, all is relative. Because all distances in the direction of motion are shortened for the moving observer, there is no comparison length for the traveling observer to use to detect the change. The equation is

​Quantum Mechanics

​Not only was classical mechanics unsuccessful in explaining motions near the speed of light, it also could not explain the behavior of matter on the atomic level. Quantum mechanics is required to analyze the behavior of molecules, atoms, and nuclei.

​Blackbody radiation

​A blackbody is an ideal thermal object that absorbs all radiation falling on it at low temperatures and is also a perfect radiator. The curves of radiation intensity versus wavelength could not be explained by classical physics. Max Planck (1858–1947) developed an equation for blackbody radiation that agreed with the data. This derivation required two assumptions:

​Blackbody radiation

​Blackbody radiation

​The radical nature of Planck’s vision is the assumption of quantized energy states. The terms discrete and quantum referred to considering the energy as coming in packets instead of as a continuous flow; thus, the molecule will change energy states only if the amount of energy absorbed or radiated is a discrete amount of energy.

Unraveling the Electron Dance

Understanding the intricate movements and interactions of electrons in various systems and materials.

Understanding Electronic Configurations

• Electronic configurations describe the arrangement of electrons in an atom.
• Electrons occupy energy levels and sublevels within those levels.
• The Pauli exclusion principle states that no two electrons can have the same set of quantum numbers.
• The Hund's rule states that electrons will occupy separate orbitals within a sublevel before pairing up.
• Electronic configurations are represented using orbital notation or electron configuration notation.

Multiple Choice

Which principle states that electrons will occupy separate orbitals within a sublevel before pairing up?

• Pauli exclusion principle

• Hund's rule

• Electronic configurations

• Orbital notation

Hund's Rule

Hund's Rule: Electrons will occupy separate orbitals within a sublevel before pairing up. This rule helps explain why some elements have unpaired electrons, which affects their chemical properties. It is an important concept in understanding electron configurations and the behavior of atoms.

The Bohr Model

The Bohr Model is a simplified view of the atom proposed by Niels Bohr in 1913. It describes electrons as orbiting the nucleus in specific energy levels or shells. Electrons can jump between these levels by absorbing or emitting energy. This model laid the foundation for our understanding of atomic structure.

Multiple Choice

What is the Bohr Model?

• A model proposed by Niels Bohr to describe the electron dance

• A simplified view of the atom that describes electrons orbiting the nucleus in specific energy levels

• A model that explains how electrons absorb or emit energy

• A model that laid the foundation for our understanding of atomic structure

Bohr Model:

A simplified view of the atom that describes electrons orbiting the nucleus in specific energy levels. This model revolutionized our understanding of atomic structure and laid the foundation for modern quantum mechanics. It introduced the concept of quantized energy levels and explained how electrons absorb or emit energy. The Bohr Model was proposed by Niels Bohr in 1913.

Understanding Quantum Mechanics

• Quantum mechanics is a branch of physics that describes the behavior of particles at the subatomic level.
• It challenges our classical understanding of physics, introducing concepts like superposition and entanglement.
• Quantum mechanics is crucial for understanding the behavior of electrons and their dance around atomic nuclei.
• It has applications in various fields, including quantum computing and quantum cryptography.

Multiple Choice

What is the branch of physics that describes the behavior of particles at the subatomic level?

• Quantum mechanics

• Classical mechanics

• Thermodynamics

• Electromagnetism

Quantum Mechanics

Trivia: Quantum mechanics is the branch of physics that describes the behavior of particles at the subatomic level. It revolutionized our understanding of the universe, challenging classical physics. It introduced concepts like wave-particle duality, superposition, and entanglement. Quantum mechanics is the foundation of modern technologies like transistors, lasers, and quantum computers.

The Aufbau Principle

The Aufbau Principle is a fundamental concept in chemistry that explains how electrons are arranged in an atom. According to this principle, electrons fill the lowest energy levels first before moving to higher energy levels. This process is known as electron configuration. The Aufbau Principle helps us understand the periodic table and predict the chemical properties of elements. It is a key concept in understanding the behavior of atoms and molecules.

Multiple Choice

What is the purpose of the Aufbau Principle in chemistry?

• To explain how electrons are arranged in an atom

• To predict the chemical properties of elements

• To understand the behavior of atoms and molecules

• To determine the electron configuration of an atom

Aufbau Principle:

The Aufbau Principle explains how electrons are arranged in an atom. It states that electrons fill the lowest energy levels first before moving to higher energy levels. This principle helps us understand the behavior of atoms and molecules, and determine the electron configuration of an atom.

Force carriers

Multiple Choice

An antiproton is an atomic particle that has:

• the mass of a proton and the charge of a neutron

• the mass of an electron and the charge of a proton

• the mass of a neutron and the charge of a proton

• the mass of a proton and the charge of an electron

Multiple Choice

A minus pion is made of a down quark and an anti-up quark. It is a

• Meson

• Baryon

• gluon

• lepton

Multiple Choice

Which of the following particles is a lepton?

• Pion

• Tau

• Proton

• Neutron

Multiple Choice

A meson is consist of 2 up quark and 1 strange quark, what is the charge of this particle?

• +1 e

• -1 e

• +2 e

• 0 e

Multiple Choice

Which of the following combination of quarks can produce a particle with the same charge as anti-proton?

• uub

• udd

• ddd

• ccs

Let's finish with a quick quiz

Multiple Choice

Which of the following force is not supported by the standard model?

• electromagnetic force

• strong nuclear force

• weak nuclear force

• gravity

Multiple Choice

Which gauge boson is responsible for electromagnetic force?

• W particles

• photons

• gluons

• Z particles

Multiple Choice

Which force has gluon as the intermediate particle?

• Electromagnetic force

• strong nuclear force

• weak nuclear force

• gravity

Multiple Choice

Which force holds nuclear together?

• electromagnetic force

• weak nuclear force

• strong nuclear force

• gravity

Multiple Choice

Which of the following is true?

• W and Y particles act between quarks and leptons.

• W particles are heavier than protons.

• Photons are force carrier of strong nuclear force.

• gluons glues photons together.