quantum physics

• Introduction to Relativity

  Relativity is a theorem formulated by Albert Einstein, which states that space and time are relative, and all motion must be relative to a frame of reference. It is a notion that states’ laws of physics are the same everywhere. This theory is simple but hard to understand.
• It states:

  • There is no absolute reference frame. One can measure velocity if the object or momentum is only in relation to other objects.
  • The speed of light is constant irrespective of who measures it or how fast the person measuring it is moving.

  Albert Einstein’s Theory of Relativity encompasses two theories: Special Relativity Theory and General Relativity Theory.
• Special Theory of Relativity was first introduced by Einstein in the year 1905.
• The Special Theory of Relativity deals with the structure of space-time.
• The Special Theory of Relativity is based on two postulates: the laws of physics are the same for all, irrespective of the observer’s velocity, and the speed of light is always constant regardless of the motion of the light source or the motion of the observer.
• The Special Theory of Relativity lays the foundation of time travel.
• According to Einstein, the rate at which time tics decreases with the increase of the person’s velocity.
• Time Dilation is the phenomenon where the rate at which time tics decreases with the increase of the person’s velocity.
• Relativity of simultaneity, as per the Special Theory of Relativity, states that two actions, simultaneous for one person, may not be simultaneous for another person in relative motion.
• Length Shrinking, another phenomenon of the Special Theory of Relativity, states that objects are measured and appear shorter in the direction they are moving with respect to the observer.
• Mass–Energy Equivalence, a concept derived from the study of relativity, states that E = mc2 where E is Energy, m stands for mass and c for the velocity of light.
• The increased relativistic weight of an object, according to the Special Theory of Relativity, is equal to the kinetic energy divided by the square of the speed of light.
• Special theory of relativity is given by the formula: E=mc^2
• The Pauli Exclusion Principle states that, in an atom or molecule, no two electrons can have the same four electronic quantum numbers.
• difference between nuclear fission and fusion

  
• Main Components of a Nuclear Reactor:

  ⦁ The Core: It contains all the fuel and generates the heat required for energy production.⦁ The Coolant: It passes through the core, absorbing the heat and transferring into turbines⦁ The Turbine: Transfers energy into the mechanical form⦁ The Cooling Tower: It eliminates the excess heat that is not converted or transferred⦁ The Containment: The enveloping structure that separated the nuclear reactor from the surrounding environment.
• Based on general use, there are two types of Nuclear Reactor

  ⦁ Nuclear Research Reactors: Exclusively for the purpose of research and testing methodologies.⦁ Nuclear Power Reactors: Established for the solitary purpose of producing energy and electricity
• Nuclear Reactors can also be classified according to the type of fuel used

  ⦁ Uranium fuelled, namely U-235 isotope as U-238 is not fissionable⦁ Plutonium fuelled
• Based on the design, there are other types of a nuclear reactor like

  ⦁ Pressurized water reactors⦁ Boiling water reactors
• radioactive decay follows first-order kinetics due to the random nature of decay and the constant probability of decay per unit time.In first-order kinetics, the rate of decay is proportional to the number of radioactive nuclei present. This means that the larger the number of radioactive nuclei, the faster the decay rate. However, the probability of decay per unit time remains constant, regardless of the number of nuclei present. This is because the decay of each nucleus is a random event, independent of the decay of other nuclei.
• Half-Life is normally defined as the time needed by a radioactive substance (or one half the atoms) to disintegrate or transform into a different substance. The principle was first discovered in 1907 by Ernest Rutherford. It is usually represented by the symbol Ug or t1/2.
• Half-Life Formulas

  1. N(t) = No (½) t / t ½ 
  2. N(t) = No e-t / r
  3. N(t) = Noe– λt

  Here we consider the following,

  • N0 = the initial quantity of the substance
  • N(t) = the quantity that is left over
  • t1⁄2 = half-life
  • τ = mean lifetime of the decaying quantity
  • λ = decay constant
• 1. Decay constant is also known as disintegration constant.
  2. It is the ratio of number of radioactive atoms disintegrating in a short interval of time to the number of atoms of same kind present at the starting.
  3. It is represented by the symbol lambda.
  4. The unit used for decay constant is s^-1.
  5. It is the reciprocal of decay time.