Physics def of G-12 myanmar

May the future g-12 students of myanmar suffer less

Rigid body

A rigid body is a body that does not deforms or change shape.

Rotational motion under constant angular acceleration

The angular velocity of the rotating object changes at a constant rate, then we can say that the angular acceleration is constant and the motion is called the rotational motion under constant angular acceleration.

Tangential velocity

Since the direction of linear velocity is tangent to the path, the linear velocity is also called tangential velocity.

Tangential acceleration

If the magnitude of the angular velocity of a rotating object changes, the magnitude of linear velocity will also change and the object will have a tangential acceleration.

Centripetal acceleration

For uniform circular motion, the centripetal acceleration vector points towards the centre of the circular path while the linear velocity vector is tangential to the path. This acceleration is called centripetal acceleration.

Centripetal force

Centripetal force is the force acting on an object in circular motion which is directed towards the axis of rotation (or) centre of curvature.

Centrifugal force

Centrifugal force in a circular motion is not a real force; it acts radially away from the centre of the circle. It results from the effect of inertia.

Centrifuge

A centrifuge is a piece of equipment that puts an object in rotation around a fixed axis (spins it in a circle).

Sedimentation principle

In a laboratory centrifuge that uses sample test tubes, the radial acceleration causes denser particles to settle to the bottom of the tube, while low density substances rise to the top. This effect is known as sedimentation principle.

Angle of banking

The angle that the inclined track makes with horizontal is called angle of banking.

Centrifugal Pump

Centrifugal pump is a hydraulic machine which converts mechanical energy into hydraulic energy (i.e., pressure energy) by the use of centrifugal force acting on the fluid.

Centrifugal Governor

The centrifugal governor is a device used to measure and regulate the speed of a machine, such as an engine.

Streamline

In the flow of fluids, the path or flow of the fluid particles is called streamline.

Laminar flow

If fluid particles are moving steady in smooth paths in layers, with each layer moving smoothly past the adjacent layers with no mixing; such a flow is called laminar flow.

Turbulent flow

If the flow or path of the fluid particles are irregular, their direction is always changing or whirling; this fluid movement is called turbulent flow.

Bernoulli's Theorem

The sum of pressure energy, kinetic energy and potential energy per unit volume of an incompressible, non- viscous fluid in a streamlined laminar flow remains constant.

Dynamic viscosity

One way to measure fluid's resistance to flow when an external force is applied. This is known as dynamic viscosity.

Kinematic viscosity

The other way is to measure the resistive flow of a fluid under the weight of gravity. It is known as kinematic viscosity.

Newton's Law of Viscosity

Newton's law of viscosity states that the shear stress between the two adjacent layers of fluid is directly proportional to the negative value of the velocity gradient between the same two adjacent fluid layers.

Viscosity

Viscosity is defined as the ratio of shearing stress to the velocity gradient.

Capillary action (Capillarity)

Capillary action is defined as the spontaneous flow of a liquid into a narrow tube or porous material.

Surface tension

Surface tension is defined as the force per unit length that acts across any line on a surface tending to pull the surface apart.

Determination of kinematic viscosity using Stokes' law

Stokes law expresses the drag force resisting the fall of small spherical objects through a fluid medium under the influence of gravity.

Energy demand

Energy demand is the consumption of energy by human activities.

Energy crisis

Energy crisis is the concern that the world's demands on the limited natural resources that are used to power industrial society are diminishing as the demand rises.

Non-renewable energy

A non- renewable energy is a natural substance that is not replenished with the speed at which it is consumed.

Renewable energy sources

Renewable energy sources (also called non- conventional energy sources) are continuously replenished by natural processes.

Solar energy

Solar energy is the radiant light and heat from the sun that has been harnessed by humans since ancient times using a range of ever - evolving technologies.

Photovoltaic effect

Conversion of light energy into electrical energy is based on a phenomenon called photovoltaic effect.

Wind energy

Wind energy is the energy generated or produced by harnessing the power of the wind.

Hydroelectric energy

The flowing water and water stored in huge dams is also very important source of energy which is known as a hydroelectric energy.

Geothermal energy

Geothermal energy is a type of renewable energy taken from the earth's core (the internal heat of the earth) and it is one of the oldest types of natural sources of heat.

Fossil fuels

Fossil fuels, such as coal, oil and natural gases, are important non - renewable sources of energy.

Acid rain

Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.

Solar cell

A solar cell (also known as photovoltaic cell) is defined as an electrical device that converts light energy into electrical energy through the photovoltaic effect.

Coalification

Coal is formed in a way similar to the other fossil fuels, though it goes through a different process called coalification.

Methane

Methane is a common gas found in swamps and is also the by- product of animals' digestive system.

Nuclear energy

Nuclear energy is non - renewable energy as the uranium fuels used are consumed in the nuclear fission reaction and hence are non - replenishable.

Irradiance

The total amount of radiation energy passing through per unit area and per unit time is called irradiance.

Solar panels

Individual solar cells can be combined to form modules commonly known as solar panels.

Biomass

Biomass is renewable organic material that comes from plants and animals.

Heat

Heat is the form of energy that can be transferred from one system to another as a result of temperature difference.

Heat conduction

Heat conduction is one mode of energy transfer. The individual parts of a medium do not move as a whole in heat conduction. Heat energy is transferred by successive distribution among the adjacent parts in heat conduction.

Thermal conductivity

Thermal conductivity of the material is a measure of the ability of a material to conduct heat.

Heat Convection

Heat convection is the flow of heat through a fluid from places of higher temperature to places of lower temperature by movement of the fluid itself.

Heat Radiation

Heat radiation is a transfer of heat that does not require a material medium. Heat is transferred by thermal radiation which are electromagnetic waves that pass through a medium or even vacuum.

Blackbody

The object which can absorb all the electromagnetic radiations falling upon it is called a blackbody.

Blackbody radiation

The radiation emitted by a blackbody is called blackbody radiation.

Total emissive power

The total emissive power is defined as the total radiant energy of different wavelengths emitted from unit area of a surface of a body in one second.

Stefan - Boltzmann's Law

The total emissive power of a blackbody is directly proportional to the fourth power of absolute temperature.

Emissivity

Emissivity is defined as the ratio of the total emissive power of an object to that of the blackbody, at the same temperature and wavelength.

Thermodynamics

Thermodynamics is the study of systems involving energy in the form of heat and work.

The Zeroth Law of Thermodynamics

When two objects are separately in thermodynamic equilibrium with a third object, they all are in thermodynamics equilibrium with each other.

First Law of Thermodynamics

The change in internal energy ΔU of a system is equal to the net heat flow Q into the system minus the total work W done by the system.

Internal Energy

The internal energy U of a system is defined as the sum of the energies of all constituted particles.

Thermodynamics process

A thermodynamics process may be defined as a change from one equilibrium state of a system to another.

Heat engine

Heat engine is a system that converts heat to mechanical energy, which can be used to do mechanical work.

Thermal efficiency

Thermal efficiency for a heat engine is the ratio of work output to heat input.

Carnot's Theorem

Carnot's theorem states that no engine operating between two heats reservoirs can be more efficient than a Carnot's engine operating between the same heat reservoirs.

Sound

Sound is a sequence of pressure wave which propagates through compressible media such as air or water.

Speed of sound wave

Speed of sound wave can also be affected by the density, temperature and elasticity of the medium through which the sound waves travel.

Intensity Level of Sound

The level of intensity of a sound is measured relative to a reference intensity value taken as 10−12Wm−210−12Wm−2 which correspond to the minimum intensity of sound that can be heard (threshold of hearing or minimum audible intensity).

Decibel (dB)

The decibel (dB) is the unit used for measuring sound intensity (intensity level of sound).

Echo

Echos are produced when a sound wave is reflected from a large and hard surface. An echo is repetition of sound due to the reflection of sound.

Audibility

Audible means able to be heard. Audibility means the ability to be heard or capability of detecting sounds in certain range of frequencies.

Range of audibility

The range of frequencies a person can hear is known as the range of audibility.

Limit of audibility

For humans with normal hearing, the lower limit is 20Hz20Hz and the the upper limit is about 20000Hz20000Hz . These limits are known as limit of audibility.

Infrasound

Low frequency sounds which are under the lower limit of audibility (20Hz)(20Hz) are called infrasound and cannot be heard by human.

Ultrasound

High frequency sounds which are above the upper limit of audibility (20000Hz)(20000Hz) are called ultrasound which cannot be heard by human ear.

Sonar

The sonar (sound navigation and ranging) is type of technology that works based on echoes.

Doppler effect

The Doppler effect or Doppler shift is the change in frequency of wave related to an observer due to the relative motion between the source and the observer.

Doppler equation

Doppler effect, the apparent frequency, f0=fs (ν∓νs​/ν±ν0​​)

Red shift

The wavelength the light from star observed from the earth's shift due to Doppler effect towards the red end of the spectrum (lower frequency, longer wavelength) when the earth and the star are moving away from each other. This phenomenon is called red shift.

Rader

Rader (radio detection and ranging) is a form of echolocation that uses electromagnetic waves instead of sound but otherwise the concept is similar.

Pitch

The pitch of the note (how high it is) is determined by its frequency. The greater the frequency, the higher is the pitch.

Quality or Timbre

Timbre is the quality of the sound which allows us to distinguish between different sound producing sound at the same pitch and loudness.

Intensity and loudness of sound related to amplitude

The intensity of the sound at a place is the energy transmitted per second per unit area held normally to direction of sound.

Intensity of a wave

The intensity of a wave is directly proportional to the square of the amplitude of the wave.

The camera

A camera is an optical instrument that forms and records an image of an object.

Convex lens

A convex lens focuses the light from the object to form a real inverted image on the film or electronic sensor.

Diaphragm

A diaphragm is placed behind the convex lens to control the amount of light energy falling on the film.

Aperture

The aperture is a circular opening through which the light passes. It can be made wide or narrow by adjusting the diaphragm. The size of the diameter of the aperture is expressed in term of f- numbers. The f- number of a camera is the ratio of the focal length of the lens to the diameter of aperture.

Shutter

A shutter controls the time during which light enters the camera through, the lens.

Focusing Ring

A camera consists of a focusing ring by which the distance between the lens and the film can be adjusted to obtain a sharp image on the film.

Film

The film at the back of the camera is actually a screen which receives the image. In a digital camera, the film is replaced by an electronic sensor. It is made up of millions of tiny pixels which response to light.

Human eye

Human eye consists of sense organs which are capable of receiving visual images and sending the information to the brain.

Farsightedness (Hyperopia)

Farsightedness is a defect of vision in which distant objects are seen clearly, but objects nearby are blurry.

Nearsightedness (Myopia)

Nearsightedness is a defect of vision in which near objects are seen clearly, but objects far away are blurry.

Least distance of distinct vision

People with normal vision can be seen an object in greatest detail when it is placed at a certain distance from the eye. This distance, which is known as the least distance of distinct vision is about 25cm25cm .

Maximum distance of distinct vision

People with normal vision can see clearly objects which are at infinity. Thus, for normal vision for the maximum distance of distinct vision is infinity.

Compound microscope

A microscope is an optical instrument which uses lenses to make enlarged images of objects that are too small for the unaided eye to see.

Magnifying power of a compound microscope

The magnifying power (MP) of a compound microscope is the product of the magnification of the objective and the magnifying power of the eyepiece.

Telescope

An optical instrument used for viewing distant objects is called a telescope.

Astronomical telescope

The refracting astronomical telescope consists of an objective of long focal length and an eyepiece of short focal length.

The magnifying power of astronomical telescope

The magnifying power (MP) of the refracting astronomical telescope is defined as the ratio of the angle ββ subtended by the image seen by the eye through the optical instrument to the angle a subtended by the object as seen without instrument.

Total reflecting prisms

Total reflecting prisms (90° 45° - 45° prisms) are used in binoculars to reduce the length of the terrestrial telescope.

Binocular

A binocular is an optical instrument which consists of a pair of telescopes one for each eye, and those telescope employ the total reflecting prism.

Laser

A laser, acronym for Light Amplification by Stimulated Emission of Radiation, is a source of a narrow beam of intense, monochromatic, coherent light in the visible, infrared or ultraviolet part of the electromagnetic radiation.

Spectrometer

A spectrometer is a scientific instrument used to separate and measure spectral components of a physical phenomenon.

Photometry

Photometry is the science of measuring visible light in units that are weighted to the sensitive of human eye. The human eye responds only to light having wavelengths between about 400 nm400 nm and 700 nm700 nm .