General Science Heat, Light and Magnetism for upsc ssc cgl preparation

General Science Heat, Light and Magnetism for upsc ssc cgl preparation


Heat:

Calorie: Is the amount of heat required to raise the temperature of 1 kg. of water to 1 degree centigrade.

Effects of Heat:

• Increase temperature and volume. 
•  Changes state.
• Brings about chemical action.
• Changes physical properties.

Temperature: Is the degree of hotness in a body.

Latent Heat: Is the heat which is spent in changing the state of a body without raising its temperature.

Evaporation: Change of state from liquid to vapor. Cooling is caused by evaporation.

Transference of Heat: Heat can be transferred in three ways.

• Conduction: The process in which heat is transferred from particle.
• Convection: The transfer of heat from on part of the body to another by the actual motion of the heated particle of a gas or liquid.
• Radiation: The process by which heat is transferred from one point to another without heating the medium.

Relegation: The process by which are joined two or more blocks of the ice by placing one above the other. It is due to the pressure that ice below melts and water again solidifies to form one mass.

Freezing Mixture: Such mixtures by means of which we can produce low temperature.

Ex:- Common salt mixed with ice.

Air Conditioning: The process of regulating the human temperature and circulation of air in a public building, office or factory.

Light:

Colour Blindness: When a person cannot distinguish between different colours (especially between green and red).

Reflection: A ray of light falling on a mirror is sent back by the law of reflection.

Laws of Reflection:

• The reflected ray, the incident ray and the normal at a point lie in the same plane.
• The angle of incidence is equal to the angle of reflection.

Refraction: When a ray of light is incident obliquely on a surface of separation between two media, part of it goes into the second medium along a path different from the direction of the incident beam. This phenomenon is called refraction.

Law of Refraction:

• The incident ray, the refracted ray and the normal at a point lie in the same plane.
• The ratio of the sine of the angle of incidence is constant, is called the refractive index of the medium.

Mirage: Is an optical illusion due to total internal reflection.

Astigmatism: One can see vertical lines clearly but not the horizontal ones or vice versa remedied by using cylindrical glasses.

Myopia(short-sightedness): A myopic person can see nearer objects distinctly but not the distant ones. Remedy: Use of concave lens.

Hypermetropia(long-sightedness): A person can see distant objects distinctly but not near ones.

Remedy: Use of convex lens.

Magnetism:

Magnet: Is a substance having a property of attracting pieces of iron, cobalt, nickel, etc. A magnet when freely suspended points towards North and South.

Lodestone: Is a compound of iron and oxygen. It attracts pieces of iron, cobalt, nickel, etc. When suspended points in the North and South directions. It is natural magnet.

Artificial Magnet: Substance that has been imparted the properties of a magnet by artificial means. This involves rubbing a magnet over a piece of steel again and again till magnetized.

Nuclear Physics:

Nuclear Physics has grown into one of the most significant branches of science, leading as it does to modern theories of atomic structure to nuclear weapons and to the production of radio-isotopes for use in industry and medicine. It began with the study of radioactivity discovered by the French Physicist Henri Bacquerel in 1896 when he found that invisible radiation from pitchblende- a mineral containing uranium could fog a photographic plate.



Important Links:

• General Science Physics Mechanics.
• General Science Laws and Definitions.
• General Awareness About Great Inventions in World.
•  General Science Physics Basics.