# General Awareness-Physics Notes-Applied Physics & Basic Physics- Part 1

## General Awareness - Online Physics Notes - Applied Physics and Basic Physics - Part I

• Sound waves are longitudinal waves.
• Sound waves cannot travel through vacuum.
• Acoustic is the subject dealing with the study of sound.
• Velocity of Sound is extreme in solid.
• The velocity of sound in air increases with increase in temperature.
• The velocity of sound in air is proportional to the square root of the absolute temperature.
• The sound of high pitch: Shrill
• The sound of low pitch: Sharp
• Hertz is the unit of frequency.
• Vibration of a string is a transverse motion.
• Stethoscope is based upon the principle of multiple reflection.
• Doppler effect describes the relationship between the pitch of sound and distance from the source of sound.
• Doppler effect: Describes to find binary stars,
• Sound signal is recorded as light signal on a cinema film.
• When sound waves enter from air into water they bend away from the normal.
• Light travels faster than sound.
• Whispering gallery; Gol Gumbaz.
• Uses of echoes: (1) Bats fly in the dark. (2) Detect the submarines under water.
• Echo: We hear original and then reflected sound.
• The obstacle should be at least 16.5 mts.
• The time interval between sound production and its echo is 1/10 of a second.
• Vibration of a string is transverse.
• Microphones convert sound into electric energy.
• Loud Speaker converts electric energy into mechanical energy and mechanical energy into sound energy.
• A sound of single frequency is called tone.
• Mach number: The ratio of the velocity of the body to the velocity of sound.
• Expression for simple harmonic motion: a Sin (Wt-Kn).
• The waves produced by the Sonometer is transverses stationary and polarized.
• Lissajous figures are very useful in comparing frequencies.
• The velocity of sound in gas is the square root of the adiabatic elasticity medium.
• The velocity of sound in air decrease with increase in pressure.
• The quality of tone depends upon the present.
• The frequencies of two vibrating systems equal it is called resonance.
• The velocity of sound in air is 332 meters/sec. 0 oC when the air is dry.
• Ultra sonics are detected by the thermal detector.
• Ultra sonic waves have frequencies higher than 20,000 Cycles per Sec.
• Infra sonic waves have the frequencies less than 20hz,
• A spherical liquid drop has a convex surface.
• Surface Tension: Soap bubble.
• The pressure inside a bubble is inversely proportional to its radius.
• Quincke's drop method is used for measuring surface tension and angle of contact for mercury in contact with glass.
• Cream separator: Centripetal force.
• Blotting paper: Capillary action.
• Adhesion: Force of attraction between unlike molecules.
• Cohension: Force of attraction between like molecules.
• Rocket: Conservation of momentum.
• Hygrometer: Instrument for measuring relative humidity.
• Tensimeter: Device for measuring vapour pressure.
• A falling in barometer: Storm.
• Ballory are filled with hydrogen.
• Sublimation: Vapourisation of a solid without first becoming a liquid.
• In pressure cooker the water boils at more than 100o C.
• Condensation: the change of vapour into liquid.
• Heat from the sun reaches the earth by way of radiation.
• Dry ice is solid carbondioxide.
• Pyrometer is used for measuring higher temp.
• When ice melts in a glass of water, the level of water in glass remains the same.
• If a ship enters into sea from the lake the level of the ship rises.
• S.I unit of heat is joule; in C.G.S system it is calorie.
• Hope's experiment proves the density of water is maximum at 4°C.
• The S.I unit of temperature is Kelvin.
• Thermostat used to maintain a constant temperature.
• Absolute zero: -273°C.
• Absolute zero: -460°F
• At -40° the Fahrenheit and Centigrade Scales are equal.
• At 574.25°F the Fahrenheit and Kelvin are equal.
• The temperature of human body is 36.9°C (fever:39°C).
• Latent heat of fusion of ice=336 x 103 J/kg.
• Regelation means refreezing.
• Thermometric scales:  F = 9/5 C + 32 = 1.8C + 32,      C = (5/9 F-32) = 0.56 F-18
• Laws of Reflection : (i) The angle of incidence is equal to the angle of reflection. (ii) The incident ray, reflected ray and normal to the surface lie in the same plane.
• Parallel Mirrors: (i) The No of images formed when an object is· kept in between two plane mirror is infinite, (ii) 3 images are formed when the two mirrors are inclained and the angle between the two mirror is 90° (5 images when the.angle.is 60°, 7 images when the angle is 45°, 11 images when the angle is 30°), (iii) The number of images formed (1) when the two mirros are inclained is equal to 1 = 360/1-1 is the angle between the mirrors, (iv) The number of images formed in Kaleidoscope is 5 (angle between the mirror is 60°). (v) Kaleidoscope and periscope are based on the principle of multiple reflection.
• Short Sight –Myopia : Eye ball too long, Focal length too small, Objects nearer are Clearly seen, Focus in front of retina, Rectified with Concave lens
• Long Sight – Hyper Metropia : Eye ball too short, Focal length too long, Objects farer are Clearly seen, Focus behind the retina, Rectified with Convex lens
• Infrared rays are discussed by William Herschell,
• Wave length between 4X10-3 m and 7.5x 107m.
• Headed zirconium and heated tungsten carbide emits infra-red.
• Infrared: Used in the treatment of Thellmatic arthritis, Used in burglar alarms, Used in Photography (dew), The remote control (TV, VCR) sends commands in the form of infrared rays.
• Ultra-violet rays are discovered by Ritter.
• Wave length between 3900 X 10-lOm and 130.x 10-lOm.
• Source-Sun and Moon: Used in Forensic science lab, Ultra-violet radiations helps for the preparation of vitamin D, Used in the treatment of bone diseases and tumors. Used for sterilizing the air in operation theatres and laboratories.
• Laser: Light amplification by stimulated emissions of Radiation.
• The laser light is coherent monochromatic and extremely intense.
• The laser beam does not diverge.
• Light is a form of Energy.
• Light particles are known as photons.
• Light waves are electromagnetic.
• Velocity of the light: 3 x 108 m/sec.
• Corpsclar theory of light: Sir Issac Newton.
• Sky is blue due to Blue light is scattered the most by small particles of atmosphere.
• Bats fly in the dark: Ultra sonics.
• Velocity of liqht: Poucaulf's rotating mirror method.
• Energy of photons: E=hr where 'h' is the Planck's constant (h =6.625 x 10-34 joules/sec)and r is the frequency of electromagnetic radiation.
• Rainbow: Dispersion.
• If a green colour leaf is seen in red light it will appear as black.
• Light travels fast in quarts.
• If a disc which has the pure spectral colours painted on it in proper proportion is rotated rapidly, it produces, white light.
• The distance between the projector and the screen, in a cinema theatre is increased by 1% the intensity of illumination is decreased by 2%.
• Click for Part II