Physics IX Notes Chapter 1 PHYSICAL QUANTITIES AND MEASUREMENT
Q.1 What is physics? Also, describe its important branches?
PHYSICS :> The branch of science which deals with the study of properties, energy and their mutual relationship is called physics”
Some important branches of physics are given below
1. Mechanics:-It deals with the motion of bodies under the action of the force.
2. Heat and thermodynamics:-It deals with the study of nature, properties. and uses of heat energy. And also deals with the transformation of heat energy from one to another form.
3. Optics:- it deals with the prorogation, reflection, refraction, dispersion, and wave properties of light.
4. Electricity and magnetism:- it deals with the study of charges at rest as well as in motion.
5. Atomic physics:-it deals with the structure and properties of an individual atom.
6. Nucleus physics:- it deals with the structure and properties of the nuclease of an atom.
7. Solid-state physics:-it deals with the properties of matter in solid-state.
8. Particle physics:- it deals with the study of elementary particles.
9. Plasma physics:-which is the fourth state of matter. And occurs in an ionized state.
10. Quantum physics:-quanta is studied is this branch which is the discrete and individuals particle of energy.
11. Semiconductor physics:- whose properties lie b/w conductor and insulator.
12. Astrophysics:- it deals with the study of heavenly bodies.
13. Biophysics:- study of biology based on the principle of physics is called biophysics.
14. Geo physics:- it deals with the study of earth and atmospheric.
15. Health physics:- it deals with the study of diseases and their treatment.
Q.2 define measurement, unit, and magnitude?
Measurement:-the comparison of an unknown quantity with some standard is called measurement.
Unit:-the standard with which things are compared is called unit-meter, kg, second.
Magnitude:- A number with a proper unit is called magnitude. eg 3kg is magnitude.
Q.3 what is meant by physical Quantities? Also, explain basic and derived quantizes?
Physical Quantity:- Those quantities which can be measured are called physical quantities.
Basic quantities:-those physical quantities which are not derived from other quantities and but other quantities are derived from they are called basic quantities. These are seven in number. The units of basic quantities are called basic units in the opposite table the units, quantities are sevenand symbols.