Modern Physics - Chapter 1
Identify the Basic Components and Application of Each Unit: 1. Joule 2. Newton 3. Coulomb 4. Farad 5. Watt 6. Ampere 7. Henry 8. Tesla
1. 1 J = 1kg * m²/s² 2. 1N = kg * m/s² 3. 1C = 6.25 × 10¹⁸ electrons 4. 1F = Q/V (Capacitance) 5. 1W = kg * m²*s⁻³ = N * m/s = J/s 6. 1A = C/s 7. kg m² * s⁻² * A⁻² [Inductance] 8. 1T = N/(A*m) = N*A⁻¹*m⁻¹
What are two fundamental conservation laws?
1. Conservation of Energy The total energy of an isolated system (on which no net external force acts) remains constant. In the case of a collision between particles, this means that the total energy of the particles before the collision is equal to the total energy of the particles after the collision. 2. Conservation of Linear Momentum The total linear momentum of an isolated system remains constant. For the collision, the total linear momentum of the particles before the collision is equal to the total linear momentum of the particles after the collision. Because linear momentum is a vector, application of this law usually gives us two equations, one for the x components and another for the y components.
Classical Kinetic Energy
A particle of mass moving with a velocity has a kinetic energy defined by: K = ½mv² K - Kinetic Energy m - mass v - velocity
Classical Momentum
A particle of mass with a velocity has a linear momentum: p = mv p - momentum v - velocity Both p and v are vectors
Angular Momentum
Angular momentum occurs when a particle moves at a displacement from the origin around which it travels. L = r × p L - Angular momentum vector r - displacement vector p - linear momentum vector
Magnetic Field produced by a current
B = ½*µ₀*i*r⁻² B - Magnetic Field µ₀ - Permeability of Free Space i - electric current in direction of positive current r - radius of circular current loop
Total Energy
E = U + K E - Total Energy U - Potential Energy K - Kinetic Energy
Coulomb Force
F = (1/4πε₀)(|q₁||q₂|/r²) q - particle charge r - distance between particles ε₀ - permitivity of free space 1/4πε₀ - constant with value 8.988 × 10⁹ N*m²/C²
Force in relation to Potential Energy
F = dU/dx F - Force U - Potential Energy
How do you calculate electrostatic potential energies easily?
For Atomic: e²/4πε₀ = 1.44 eV * nm Now divide by the number of nm (nanometers) of separation For nuclear: e²/4πε₀ = 1.44 MeV * fm Now divide
Conservation of Angular Momentum
In physics, angular momentum (rarely, moment of momentum or rotational momentum) is the rotational analog of linear momentum. It is an important quantity in physics because it is a conserved quantity - the angular momentum of a system remains constant unless acted on by an external torque.
Classical Kinetic Energy in Terms of Linear Momentum
K = p² / 2m K - Kinetic Energy p - linear momentum m - mass
Modern Physics
Modern physics is an effort to understand the underlying processes of the interactions of matter utilizing the tools of science & engineering. It implies that nineteenth century descriptions of phenomena are not sufficient to describe nature as observed with modern instruments. This area of physics usually refers to developments that began in about 1900 and led to the relativity and quantum theories
Classical Physics
Physics that does not make use of quantum mechanics or the theory of relativity. Newtonian mechanics, thermodynamics, and Maxwell's theory of electromagnetism are all examples of classical physics.
Permeability of Free Space
The permeability constant (µ₀), also known as the magnetic constant or the permeability of free space, is a measure of the amount of resistance encountered when forming a magnetic field in a classical vacuum. The magnetic constant has the exact (defined) value µ₀ = 4π × 10⁻⁷ H = 4π × 10⁻⁷ N*s²*C⁻²
Permittivity of Free Space
The permittivity of free space is a constant of proportionality that exists between electric displacement and electric field intensity in a given medium. In many materials, particularly glass and certain plastics, is substantially greater than ε₀. If ε₀ represents the permittivity of free space (that is, 8.85 x 10⁻¹² F/m) and εs represents the permittivity of a particular substance (also specified in farads per meter), then the relative permittivity, also called the dielectric constant εr, of that particular substance is given by: εr = εs/ε₀
Potential Energy [related to Coulomb Force]
U = [1/4πε₀]*[q₁q₂/r]
Dielectric Constant
a quantity measuring the ability of a substance to store electrical energy in an electric field
electron-volt
a unit of energy equal to the work done on an electron in accelerating it through a potential difference of one volt (eV) and is approximately 1.609 × 10⁻¹⁹ joules keV = kilo electron-volt = 10³ eV MeV = mega electron-volt = 10⁶ eV GeV = giga electron-volt = 10⁹ eV
Weber
the SI unit of magnetic flux, causing the electromotive force of one volt in a circuit of one turn when generated or removed in one second
Potential Difference
the difference of electrical potential between two points ∆V = ∆U/q V - Potential Difference U - Potential Energy q - charge
Magnetic Moment
the property of a magnet that interacts with an applied field to give a mechanical moment |µ| = iA A - geometrical area enclosed by the loop Direction of µ is perpendicular to the plane of the loop
Classical Velocity Addition
v₁₃ = v₁₂ + v₂₃ where v is a vector
