Q1: What is Physics ? Discuss the importance of physics ?
Ans: The branch of science which deals with the properties of matter, energy and their mutual relationship is known as physics.
Importance of physics:
Physics has played an important role in our daily life. For example,
- Atomic bomb is the invention of physics which can be use for defense purposes as well as for the production of tremendous amount of energy.
- X-rays, Laser rays, r-rays (Gamma rays) etc are the invention of physics which can be use in industry, health, detection department and agriculture department for various purposes.
- The computers and other electronic machines which make our work easier, works on the principles of physics.
- T.V loud speakers etc are electronic devices which works on the principle of physics.
- Capacitors, Inductors, transformers etc are the invention of physics which plays a vital role in electric circuits.
- Aeroplanes , buses, railways etc are the means of transport which works on the principles of physics.
- Electricity is the invention of physics without which we cannot imagine any machine in working conditions.
- Rockets and satellites are the invention of physics with the help of which we can get information about upper atmosphere.
- The simple machines like pulley, wedge, lever, wheel and axle, inclined plane etc are the invention of physics which can be used for various purposes in our daily life.
Q2: Discuss the various branches of physics?
Ans: The various branches of physics are given below.
1: Mechanics :
The branch of physics which deals with the motion of material objects under the action of forces is known as mechanics.
2: Heat and Thermodynamics:
This branch of physics deals with the study of nature, properties and uses of heat energy. It also deals with the transformation of heat energy into other forms of energy.
3: Optics:
It is the branch of physics which deals with the nature of light, its propagation, reflection, refraction, dispersion and the wave properties of light.
4: Electricity and magnetism:
It is the branch of physics which deals with the properties of charges at rest as well as in motion.
5: Atomic physics:
The branch of physics which deals with the structure and properties of individual atom is known as atomic physics.
6: Nuclear physics:
It is the branch of physics which deals with the structure and properties of atomic nuclei of an atom.
7: Solid state physics:
The branch of physics which deals with the physical properties of solids is known as solid state physics.
8: Particle physics:
The branch of physics which deals with study of sub-atomic particles (elementary particles) is known as particle physics.
9: Plazma physics:
The study of plazma is known as plazma physics. Plazma is called the fourth state of matter. It occurs in ionized state.
10: Quantum physics:
The study of quanta is known as Quantum physics.
Quanta is discrete and indivisible units of energy. The concept of quanta was given by plank in his quantum theory.
11: Semi conductor physics:
The study of semi-conductor materials is known as semi-conductor physics. Semi-conductors are those materials whose electric properties lies in between those of insulator and conductors.
12: Astro physics:
The study of heavenly bodies is known as Astro physics.
13: Bio physics:
The study of biology based on the principles of physics in known as bio physics.
14: Geo physics:
The of earth and its atmosphere is known as geo physics.
15: Health physics:
The branch of physics which deals with the study of diseases and their treatment is known as health physics.
Q3: Define measurement, unit and magnitude ?
Ans: (1) Measurement:
The comparison of something with some standard is known as measurement.
2: Unit:
The standard with which things are compared is known as unit.
3: Magnitude:
A number with proper unit is known as magnitude. For example , “13 cm” represents magnitude, where ‘13’ is purely a number while ‘cm’ is a unit of length.
Q4: What do you meant by physical quantities. Discuss its types ?
Ans: Physical quantities: Those quantities which can be measured are known as physical quantities.
Type of physical quantities:
There are two types of physical quantities which are given below.
(1) Base physical quantities
(2) Derived physical quantities
1 Base physical quantities:
These are those physical quantities in terms of which other physical quantities can be defined.
There are seven base quantities which are given below.
(1) Mass (2) Length (3) Time (4) Current (5) Temperature (6) Intensity (7) Amount of substance.
Basic unit :
The unit of base physical quantity is known as basic unit.
The name of seven base quantities, their units and symbols are given in the following table.
Base Quantity
|
Symbol
|
Unit of Base Quantity
|
Symbol
|
1. Length
|
L
|
Meter
|
m
|
2. Mass
|
M
|
Kilogram
|
kg
|
3. Time
|
T
|
Second
|
s
|
4. Electric current
|
I
|
Ampere
|
A
|
5. Temperature
|
T
|
Kelvin
|
K
|
6. Intensity of light
|
L
|
candela
|
cd
|
7. Amount of substance
|
n
|
Mole
|
mol
|
2 Derived physical quantities:
Those quantities which can be derived from base quantities are known as derived physical quantities.
For example, work, power, energy, area, etc are derived physical quantities.
Derived Unit:
The unit of derived physical quantity is known as derived unit.
For example, “meter/second” is the derived unit of speed. [speed is derived Quantity]
Some of the derived physical quantities and their units are given in the following table.
S:No
|
Derived physical Quantity
|
Unit of derived physical Quantity
|
Symbol
|
01
|
Force
|
Newton
|
N
|
02
|
work
|
joule
|
J
|
03
|
power
|
watt
|
W
|
04
|
pressure
|
Pascal
|
pa
|
05
|
speed
|
Meter/second
|
m/sec
|
06
|
Electric charge
|
coulomb
|
c
|
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