• Lactometers and Hydrometers are based on the Archimedes’ principle.

• Archimedes’ principle states that “The upward buoyant force that is exerted on a body immersed in a fluid, whether partially or fully submerged, is equal to the weight of the fluid that the body displaces and acts in the upward direction at the center of mass of the displaced fluid.”

Twin Paradox is generally related to the theory of relativity.

• This paradox experiment involve twin identical, one of whom makes a space journey in a high speed rocket and returns home to find that the another twin has aged more.

• The paradox is solved by special relativity framework.

• It was also confirmed in particle accelerators by measuring the time dilation of circulating particle beams.

• Theory of Relativity was given by Albert Einstein and encompasses two interrelated theories by Albert Einstein: special relativity and general relativity.

● The process of transformation of a substance from a gaseous state into a liquid state due to change in pressure or temperature of the substance is called condensation.

* Tesla is the unit of Magnetic field strength.

* Ohm is the unit of Electrical Resistance.

* Weber is the unit of Magnetic Flux.

* Gauss is the unit of measurement of magnetic flux density.

* The SI derivation of Unit Tesla is - kg⋅s⁻²⋅A^{−1 .}One tesla is equal to one weber per square metre.

* The innovative concept of using sunshine to keep house warm in freezing winters is called “Passive Solar Heating”.

* Passive solar heating is the process of using specific building systems to help regulate internal temperature by using the Sun's energy selectively and beneficially in an attempt to improve the energy efficiency.

• The SI unit of length is Metre.

• SI system has seven base units, which are as follows-

• The force of attraction between an electron revolving around the nucleus and the nucleus is called electric force.

• The photovoltaic cell is used to convert solar energy into electrical energy.
• It is a specialized semiconductor diode that converts visible light into direct current (DC).
• It works by allowing photons to knock free electrons from atoms that generates a flow of electricity.