GK 2015 Question Bank CD - Importance of Laws and Principles

Archimedes Principle :

• When a body is immersed either wholly or partially in a fluid at rest, the apparent loss of weight suffered by it is equal to the weight of the fluid displaced by it.

• Equal volumes of all gases under the same conditions of temperature and pressure contain equal number of molecules.

• A black body absorbs heat or radiates heat more quickly than any other body. Boiling Point :

• It increases with the increase of pressure.
• The presence of impurities also raises the boiling point of a liquid.

Centre of Gravity :

• A body will remain at rest only if the vertical line through the centres of gravity passes through the base of support of the body.

Coulombs Law :

• The force between the two electric charges reduces to a quarter of its former value when the distance between them is doubled.

• The amount of chemical change during electrolysis is proportional to the charge passed.
• The masses of substances liberated or deposited by the same quantity of electric charge are proportional to their chemical equivalents.

Law of Conservation Of Matter :

• In chemical changes, matter is neither created nor destroyed.
• The sum total of the masses of all the products of a chemical change is exactly equal to the sum total of the substances from which these products have been formed.

Laws of Thermodynamics :

• The amount of heat given to a system is equal to the sum of the increase in the internal energy of the system and the external work done.
• It is impossible to construct a continuous self-acting machine that can pump heat energy from a body at lower temperature to a body at higher temperature.

Lenzs Law :

• When an electric current is induced by a change in magnetic field, the induced current is always in such a direction that its magnetic field opposes the change of field which causes the induction.

Mass – Energy Equation :

• E = mc2, where E = quantity of energy released from the annihilation of matter of mass ‘m’, c = velocity of light.
• It implies that mass and energy are interchangeable.

Newtons Law of Cooling :

• The rate at which a body cools or loses its heat to its surroundings is proportional to the excess of mean temperature of the body over that of the surroundings, provided this temperature excess is not too large.

Newtons Universal Law of Gravitation :

• Every body in the universe attracts every other body with a force, directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

Newtons Laws of Motion :

• Everybody continues in its state of rest or of uniform motion in a straight line unless it is compelled to change that state by a force ( called Law of Inertia ).
• The rate of change of momentum of a moving body is proportional to the applied force and takes place in the direction of the force.
• For every action there is an equal and opposite reaction.

Ohms Law :

• The amount of current flowing in an electric circuit is governed by the voltage of the battery on dynamo which powers it.
• In other words, the current through a conductor is directly proportional the potential difference across the conductor and inversely proportional to its resistance.

Rectilinear Propagation of Light :

• Light travels in a straight line.
• Total internal reflection takes place when a ray of light tries to pass from a denser medium to a rarer medium at an angle of incidence more than the critical angle. 