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Answer The study of nature may be classified into two branches
1.biological Science
The science of Living things is called Biological science
2. Physical Science
The science of non-living things is called Physical science Physics:
Physics the branch of science concerned with properties of matter and energy and the relationship between them
In other words physics is basically the study of how objects behave.
Physics is an important and the basic part of physical science It is the experimental science
Q.2. Describe the main frontiers of fundamental science. Describe some new branches of physics
Answer There are three main frontier of fundamental science
1) The world of extremely large (e universe).
2 The world of the extremely small (i e particles such as electrons, protons, neutrons, mesons and others)
3) The world of middle sized things from molecule at one extreme to the Earth at the other it is the world of complex matter.
By the end of 19th century many physicists started believing that everything about physics has been discovered However, about the beginning of the 20 century many new experimental facts revealed that the laws formulated by the previous investigations need modification
1. Nuclear physics
The branch of physics which deals with atomic nuclei is called nuclear Physics
2. Particle physics
The branch of Physics which is concerned with ultimate particles of which matter is composed is called particle Physics
3. Relativistic Mechanics
The branch of Physics which deals with velocities aching that of light is called relativistic mechanics
4. Solid State Physics
The branch of Physics which is concerned with the structure and properties of solids is called soud state Physics
Other Branch of Physics
Physics is most fundamental i all sciences and provides other branches of science basic principle and fundamental law The overlapping of physical and other fields gave birth to new branches5. Astrophysics
The branch of Physics concerned with physical and chemical properties, origin and evolution of the
6. Biophysics
The branch of physics which deals with scientific study of biological processes in terms of the law of Physics For example Echolocation in bats and Stresses and strains in skeletal and muscular structures
7. Aerodynamics
The branch of physics which deals with the study of the movement of air and other gases includes the study of the interaction of air with moving objects Such as airplanes and of the effects of moving air on stationary objects such as buildings
8. Cosmology
The branch of physics which deals with the behaviour of the material universe in its entirety It is the one of widest subjects in the spectrum of Physics
9. Physical Chemistry
The branch of chemistry that is concerned with physical structure of chemical compounds. the amount of energy they have, the way they react with other compounds and the bonds that hold their atoms together
10. Physical Oceanography
It is the study of physical conditions and physical processes within the ocean, especially the motions and physical properties of ocean waves
11. Medical Physics
It is application of physics to medicine i generally concerns physics as applied to medical imaging and radiotherapy
12. Geophysics
It is the physics of the Earth and its environment in space Its subjects include the shape of the Earth its gravitational and magnetic fields, the dynamics of the Earth as a whole and of its component parts. the Earth's internal structure composition and tectonics, the generation of magmas volcanism and rock formation, the hydrological cycle including snow and ice, all aspects of the oceans, the atmosphere. ionosphere, magnetosphere and solar-terrestrial relations and analogous problems associated with the moon and other planets
13. Engineering Physics (EP)
It is an academic degree available mainly a the levels of B.Tech, B.Sc. MSc and PhD Unlike other engineering degrees (such as aerospace engineering or electrical engineering) EP does not necessarily include a particular branch of science or Physics Instead EP provides a more thorough grounding in applied Physics of any area chosen by the student (such as optics nanotechnology micro fabrication, mechanical engineering electrical engineering control theory aerodynamics energy or solid state Physics
14. Plasma
A plasma s a gas in which an important fraction of the atoms is ionized so that the electronics and 16. ions are separately free in Physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized The basic premise is that heating a gas dissociates its molecular bonds, rendering it into its constituents particles positive ions and negative electrons
The presence of a non-negligible number of charge carriers makes the plasma plectrical conductivity to that it responds strongly to electromagnetic fields Plasma therefore has properties quite unlike those of solids, liquids or gases and is considered a distinct state of matter Like gas plasma does not have a definite shape or a definite volume unless enclosed in a container like gas under the influence of a magnetic field it may form structures such as filaments beams and double layers Some common plasma are stars and neon
15. Magneto Hydrodynamics (MHD)
Magneto fluid dynamics or hydro magnetic is the branch of Physics which studies the dynamics of electrically conducting fluids
Examples of such fluids include plasma liquid metals, and salt water The word magnetohydrodynamic (MHD) is derived from magneto - meaning magnetic field and hydro-meaning liquid and dynamics meaning movement The idea of MHD is that magnetic fields can induce current in a moving conductive fluid, which create forces on the fluid, and also change the magnetic field itself 16. Space Physics
It is also known as space plasma physics It is the study of plasmas as they occur naturally in the universe As sucht encompasses a far-ranging number of topics. including the sun, solar wind planetary magnetosphere and ionospheres auroras, cosmic rays and synchrotron radiation Space Physics is a fundamental part of the study of space weather and has important implication not only to understanding the universe, but also to practical every day life, including the operating of communications and weather satellites
Space Physics is unique from other fields of astrophysics which study similar phenomenon in that Space Physics utilizes measurements from high altitude rockets and spacecraft
17. Super fluidity
It is state of master in which the matter benaves like a fluid without viscosity and with infinite thermal conductivity The substance which looks like a liquid, will flow uncontrollably, and also will be at exactly the same temperature throughout itself.
Superfluidity is the frictionless flow and other exotic behavior observed in liquid hehum ar temperatures near absolute zero (-273 15°C or -459 67"F), and (less widely used) similar functionless behavior of electrons in a superconducting solid
18. Superconductivity.
It is an electrical resistance of exactly zero which occurs in certain material below characteristic temperature weak interaction and gravitation
Electromagnetism is the force that causes the interaction between electrically charged particles the areas in which this happens are called electromagnetic fields Electromagnetism in also the force which holds electrons and protons together inside atoms which are the building blocks of molecules This governs the processes involved in chemistry which anse from interactions between the electrons inside and between atoms
Q.3. What are physical quantities? Discuss its different types and to measure the base quantities.
Physical Quantities
All those quantities in terms of which law of physics can be described are called physical quantities Types of Physical Quantities
Physical quantities are divided into.
i) Base Quantities
ii) Derived Quantities
Base Quantities
The minimum number of those physical quantities in terms of which other physical quantities can be defined are called base quantities
Example: length, ass time etc
Derived Quantities
Physical quantities whose definitions are based on other physical quantities are called derived quantities
Example: velocity acceleration momentum force etc
Measurement of Base Quantities The measurement of base quantities involves two steps
0 The choice of standard
(n) The procedure for comparing the quantity to be measured with standard Properties of an Ideal Standard
An ideal standard has two principal characteristics
It is accessible
(i) It is invariable
These two requirements are often incompatible and compromise has to be made between them 0.4. What is international system of units Discuss the units upon which it is build up Answer
International System of Unit
In 1960 an international committee agreed on a set of definitions and standard to describe the physical quantities The system that was established is called the system international (SI) The system international is formed from three kinds of unit
- (1) Base units
- (2) Supplementary units
- (3) Derived units
Standard definitions of base units
() Meter
The distance travelled by light in vacuum during a time of 1/299.792 458 second (1) Kilogram
It is defined as the mass of a Platinum (90%) and iridium (10%) alloy cylinder 3.9 cm in diameter and 39 cm in height Kept at the International Bureau of Weights and Measures in France This mass standard was established in 1901
(ii) Second
The duration in which the outermost electron of the cesium 133 atoms makes 9192631770 vibrations
Kelvin
It is the fraction 1/273 16 of the thermodynamics temperature of the triple point of water
Ampere
The unit of electric current is ampere It is that constant current which if maintained in two straight parallel conductors of infinite length of negligible circular cross-section and placed a meter of length
Candela
The unit of luminous intensity is candela It is defined as the luminous intensity in the perpendicular direction of a surface of 1/60000 square meter of a black body radiator at the solidification temperature of platinum under standard atmospheric pressure
(vii) Mole
The mole is the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kg if carbon 12 one mole of any substance contains 6.0225 x 10 entities
(2) Supplementary Units
The units which are neither base units nor derived units are called supplementary units They are
- Plane angle
- The solid angle
Standard Definitions of Supplementary Units
(i) Radian
It is the plant angle between two radii of a circle which cut off on the circumference on arc equal in length to the radius of the circle It is shown in figure
(ii) Steradian
It is the solid angle (three dimensional angle) subtended at the center of sphere an area of its surface equal to square the radius of the sphere. It is shown in figure
