basic physics concepts important Gk topic for competitive exam Part 2

basic physics concepts important Gk topic

basic physics concepts part 2 -----

READ First -----   basic physics concepts important Gk topic for competitive exam Part 1


  • Elasticity and plasticity : The property by virtue of which the body regains its original shape after the removal of deforming forcer is called elasticity. And if the body retains its deformed shape after the removal of deforming force is called plasticity.
  • Rubber is less elastic than steel.
  • Pressure is defined as force acting normally on an unit area of the surface. Its unit is N/m2. It is a scalar quantity.
  • Atmospheric pressure is measured by
  • Sudden fall in barometric reading is the indication of storm.
  • Slow fall in barometric reading is the indication of rain.
  • Slow rise in the barometric reading is the indication of clear weather.

Atmospheric pressure decreases with altitude.

  • It is difficult to cook on the mountain.
  • The fountain pen of a passenger leaks in aero plane.
  • Bleeding occurs from the nose of the man.
  • It is difficult to breath on higher altitude due to less amount of air.
  • Water starts to boil below 100o C.

Archimedes’ Principle :

When a body is immersed partly or wholly in a liquid, there is an apparent loss in the weight of the body. Which is equal to the weight of liquid displaced by the body.

  • All object placed in a liquid experience an upward force called the buoyant force and the law is called the law of buoyancy.
  • The weight of water displaced by an iron ball is less than its own weight. Whereas water displaced by the immersed portion of a ship is equal to its weight. So, small ball of iron ball sink in water, but large ship float.
  • Density of water is maximum at 4oC.
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  • Heat is a from of energy which causes sensation of hotness or coldness. Its unit is joule or calorie.
    1 cal = 4.2 joule
  • It always flows from a substance at a higher temperature to the substance at lower temperature.
    It indicates the degree of hotness or coldness of a body.
  • Heat Temperature is measured by thermometer.
  • Temperature measuring units are Kelvin, oC or oF.

Relation between Temperature on different scales.
C/5 = F-32/9=R/4=K-273/5=Ra-492/9

  • The normal temperature of a human body is 37oC of 98.6oF.
  • At-40o temperature, Celsius and Fahrenheit thermometers read the same.

Conduction: It is that mode of transmission of heat in solid where heat is transferred from a region of higher temperature to a region of lower temperature by the aid of particles of the body without their actual migration.
Convection : It requires a medium and is the process in which heat is transferred from one place to other by actual movement of heated substance (usually molecule of fluid).

Radiation : has the following properties:

  • Radiant energy travels in straight lines and when some object is placed in the path, its shadow is formed at the detector.
  • It is reflected and refracted or can be made to interfere.
    It can travel through vacuum.

Latent Heat

  • The amount of heat required to change phase (liquid to gas or liquid to solid etc.) without change in temperature is called latent heat.
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Specific Heat

  • The amount of heat that required to raise the temperature of a unit mass of a substance by one degree (14.5oC to 15.5oC) is known as Specific heat.

Sublimation :
It is the process of conversion of a solid directly into vapour, eg., lodine (dark solid), Dry ice (solid CO2), etc.
Hoar Frost : It is just the reverse process of sublimation. E.g. Frost and snowflakes.


  • A wave is a kind of oscillation (disturbance) that travels through space and matter.
  • Wave motions transfer energy, not matter from one place to another.
  • Transverse wave – In it the vibrations of particles are perpendicular to the direction to travel of the wave, It has crests and troughs.
  • Longitudinal wave :- In it the vibrations of particles are parallel to the direction of travel of wave. It has compressions and rarefactions.
  • Echo : The repetition of sound due to reflection of sound waves, is called an echo.
  • Sonar : It stands for sound navigation and ranging. It is used to measure the depth of a sea to locate the enemy submarines and shipwrecks.

Anatomy of an Electromagnetic Wave

  • Charged particles, such as electrons and protons create electromagnetic fields when they move, and these field transport the type of energy we call electromagnetic radiation, or light.
  • Mechanical waves and electro-magnetic waves are two important ways through which energy is transported in the world us.
  • Waves in water and sound waves in air are two examples of mechanical waves.
  • Mechanical waves are caused by a disturbance or vibration in matter, whether solid, gas, liquid or plasma.
  • Electromagnetic waves differ from mechanical waves in that they do not require a medium to propagate.
  • Examples of electromagnetic waves are light, radio waves, X-rays etc.
  • Sound waves cannot travel in the vacuum because there is no medium to transmit these mechanical waves.
  • Sound is transmitted through gases, plasma, and liquids as longitudinal waves, also called compression waves.
  • It requires a medium to propagate.
  • Audible sound for human is from 20 Hz to about 20000 hz.
  • Pitch is the property of sound that we perceive as higher and lower tones.
  • Sounds higher that 20000 Hz are called ultrasonics.
  • Sounds less than 20Hz are called infrasonics.
  • When temperature is increased the speed of sound is increased.
  • Speed of sound in air is 330 m/s.
  • Transparent, translucent and opaque matter
Read -  basic physics concepts important Gk topic for competitive exam Part 3

(Matter --- Nature --- Example )

  • Transparent --- It allows most of light to pass through.--- Glass, water, etc
  • Translucent --- It allows a part of light falling on it to pass through. --- Oiled paper
  • Opaque --- It does not allow the incident light to pass-through. --- Mirror, metal, wood, etc.

    Speed of Sound in Different Mediums

    {Medium ---- Speed of sound (In m/s)}

  • Air (0oC) --- 332
  • Air (20oC) --- 343
  • Iron --- 5130
  • Glass --- 5640

units of Measurement,Fundamental units,Si units important gk

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