WAEC PHYSICS DEFINITIONS

hazards of over exposure to x rays

- cause leukaemia can damage riving tissues - cause genetic mutation - cause damage to cells of large animals.

electric potential

-as the work done in an electric field per unit positive charge, in moving the unit positive charge from that point at a place at zero potential

conditions for total internal reflection of light

-light should travel from an optically denser medium to an optically less denser medium. -the angle of incidence in the denser medium should be greater than critical angle for that pair of media

factors that affect the value of acceleration of free fall

-the mass of the object -the distance of an object from the surface of the earth

interference of wave patterns to be formed

-two waves must meet at a point the particles of the medium at that point are subjected to the two different disturbances at the same time -two waves must meet in phase, their amplitude added up to produce a large wave

beam of polarised light

a beam of polarised light is the collection of rays which are restricted to move in one direction. due to the fact that light is a transverse wave, the vibrations of its matter are perpendicular to the direction of propagation of its wave motion

echo

an echo is a sound heard after the reflection of sound waves from a plane surface

angle of contact

angle of contact is the acute angle which is miniscus of liquid makes with the glass in a capillary tube

factors that determine the deviation of a ray light by a triangular prism

angle of incidence refracting angle of prism

linear momentum

the product of mass and velocity

wave-particle duality of light

wave particle of light refers to the idea that light and matter such as electrons have both waves and and particle properties, light behaves either as wave or as a particle but as both simultaneously

dielectric substances

A dielectric is an insulating material (solid, liquid or gas) separating the two plates of a capacitor.

advantages & disadvantages of a convex mirror

A: the mirror gives erect image of an object behind the driver as it also provides a wide field view when used as driving mirror D:disadvantage of convex is that it always give false impression of true distance of the object to the driver as the image is smaller or diminished which makes it dangerous as a driving mirror

factors that affect evaporation

Airflow Humidity (warm air can hold more water than cold air- as air reaches saturation point more air will condense) Temperature S.a of object Amount of energy Availability of water

two inferences that can be drawn from Brownian motion

Brownian motion is the rapid, constant and irregular movement of tiny particles

doopler effect

Doppler effect in physics is defined as the increase (or decrease) in the frequency of sound, light, or other waves as the source and observer move towards (or away from) each other

diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

uses of polaroid

Polaroids are used in glass windows of an airplane to control the intensity of light entering the airplane. Polaroid glasses are used to view three-dimensional pictures and movies. They are used to eliminate the head light glare in motor cars

loop in electrical network

a loop in an electrical network is where a voltage drop is encountered

inertial mass

a mass of a body is the qualitative measure of the inertial of the body. the more mass a body gather the force required to change its state of rest.

nuclear fission

a nuclear reaction in which a heavy nucleus splits spontaneously or on impact with another particle, with the release of energy.

cations

a positively charged ion which are attracted to the cathode

projectile

a projectile is a motion of a body moving along a curved path

electric field intensity

at any point in an electric field is defined as the electrostatic force experienced by a unit positive test charge at that point

plane polarized light

can be produced using polarizers such as tourmaline crystals, Quartz or a polaroid; polarizers allow light vibrations of only a particular direction to pass through them

uses of the laser: communication medicine security

communication: they are used as telephone fibre drivers medicine: it is used in cosmetic surgery for removing scars security: it guards against indiscrimate constant of valued properties

state three types of of emission spectra

continuous spectra, line spectra, band spectra

critical angle

critical angle the angle of incidence in the denser medium when the angle of refraction is the less dense medium

relative density

density of the substance/density of water

two waves that can be plane polarized

electromagnetic waves mechanical waves on string

electromotive force

electromotive force of a cell is defined as the potential difference between the terminals of a cell when it is not delivering any current in an external circuits or when it is an open circuit

application of electrolysis

electroplating of one metal by another it is applicable in the extraction and purification of metal

effects to show that radiation behave like particles

emission and absorption of light when a single x ray photon collides with a free electrons, the electron recoils off as through it were a perfectly elastic sphere this is known as the Compton effect

elastic constant

force experienced by the material per unit extension of the material

laws of solid friction

friction opposes motion; the limiting frictional force is independent of the area in contact

difference between hard and soft x rays

hard x rays - are those that have high penetrating power, very short wavelength or high frequency, produced at high voltages soft x rays- are those with lower penetrating power, produced at lower voltage, lower frequency

applications of plane polarized light

in the polaroid's in photo elasticity in films

law of conservation of linear momentum

in the system of colliding objects the total momentum is conserved, provided there is no external force acting on it

difference between interference and polarisation as applied to waves

interferences take place takes place when two identical waves(transverse and longitudinal) travelling in the same direction are super imposed while polarisation Only transverse waves can be polarised

ionization potential

ionization potential is the energy required to remove completely an electron from its atom

antinode

is a point on a stationary wave where there is maximum displacement of the medium

stationary wave

is a wave obtained when two progressive waves of equal amplitude and frequency are travelling in opposite direction and combined together

gravitational field intensity

is the force per unit mass acting on a mass acting on a mass at that point

Nuclear Fusion

is the process in which light nuclides combine to give heavier nuclides. mass is also lost in the process and energy is released

boiling point of a liquid

is the temperature at which the liquid saturated vapour pressure equals to atmospheric pressure

inertial

is the tendency for a body to remain to it

elasticity of a substance

is the tendency to regain its original shape and size after undergoing a stretching or compression

wave motion

it a process of transferring a disturbance from one point to another

machine

it essentially a device tool which allows a force (or effort ) applied at one point

state advantages of alcohol over mercury as thermometric liquid

it freezes at 115o whereas mercury freezes at 39o. alcohol can therefore be used for measuring very low temperature the expansivity of alcohol is about six times that of mercury rises again

wave characteristics of neutrons

it has mass on one neutron has no charge they are found at the centre of nucleus

resonance

it is a phenomenon in which an external force or a vibrating system forces another system around it to vibrate with greater amplitude at a specified frequency of operation

Transmutation as it relates to radioactivity

it is the emission of radiation by most radioactive elements is accompanies by the gradual disintegration or decay of the original element and the appearance of a new one

applications of echo

it is used for gas exploration it is used in the determination of sea depth

applications of photo electric emission

it is used in burglar alarms it is used in photocell for measuring the illumination of surface it is used in television camera it is used in automatic devices for switching on light dusk

specific heat capacity

its defined as the quantity of heat required to raise the temperature of a unit mass by one degree celsius

elasticity

its the ability of a body to regain it normal shape and size after undergoing a stretch or compression

surface tension

its the force which acts parallel to the face of the liquid which makes it behave as if its covered with elastic skin

neutral point in a magnetic field

its the point at which resulted magnetic flux density is zero

elastic limit

its when a wire is said to have lost its elasticity

magnetic line force

magnetic line force are imaginary lines along which a free north-pole would tend to move if placed on the field

wave particle paradox

matter sometimes behave as a wave and other times as particles.(same as wave particle duality)

why mecury does nor wet glass while water

mercury does not wet glass because of the force of cohesion of mercury molecules is greater than the adhesion between the glass and mercury molecules

half life

period of substance defined as the time taken for half of the atoms in any given substance to decay

difference between polarized and ordinary light

plane polarized height : light particle obtains vibration in one direction light intensity vary passing through crystals ordinary light: light particle vibrates in all directions light intensity remains unchanged if passed through a rotating crystals

polarizer

polarizer is an optical filter that passes light of specific polarization and block waves of other polarizations

differences of radio waves and sound waves

radio wave can travel through a vacuum while sound wave cannot radio wave is electromagnetic wave while sound wave is a mechanical wave

reactance

reactance of a capacitor is its opposition in ohms to the passage of alternating current.

brownian motion

refers to the random movement displayed by small particles that are suspended in fluids

the principle of conservation energy

states that an isolated or closed system, the total amount of energy is always constant, although energy may change from one form to another

law of floatation

states that an object will float in a fluid (liquid or gas) when the up thrust exerted upon it by fluid in which floats equals the weight of the object

stopping potential

stopping potential is related to the maximum kinetic energy of the ejected electrons

conditions of equilibrium for a number of coplanar parallel forces

sum of clockwise moment equals sum of anticlockwise moment sum of upward forces equal sum of downward forces

Factors that affect the rate of diffusion

temperature pressure surface area

Young's Modulus

tensile stress / tensile strain

explain why water in a narrow glass tube has a concave meniscus while mecury, in the same tube, has convex meniscus

the adhesive forces cause the water to have concave meniscus while the adhesion of mercury to glass is much less than the cohesion of mercury molecules. hence the mercury has convex meniscus

hookes law

the extension is proportional to the load within the elastic limit

kirchhoffs second law

the mass liberated by the passage of one coulomb of electricity

the principle of operation of potentiometer

the potential across any piece of the wire is directly proportional to the length of the wire, which has a uniform cross-sectional area and the constant current flowing through it

characteristic of pressure in liquid

the pressure of the liquid increases in direct proportion to the depth of the liquid the pressure in different liquid at the same depth varies directly with the density of the liquid the pressure at any point in the liquid act equally in all directions the pressure at all points at the same level within liquid is the same

principal focus

the principal focus of a convex mirror is the point from which all rays parallel and close to the principal axis appear to diverge after reflection

Heisenberg's uncertainty principle

the principle stating that due to the wave-particle duality, it is fundamentally impossible to precisely determine both the position and velocity of a particle at a given moment in time

electric potential energy

the product of a charge q and the potential difference W =qv

newtons second law of motion

the rate of change of momentum of a body per unit time is directly proportional to the force causing the change

laws of refraction of light

the ratio of sin of angle of incidence to the sin of angle of refraction is a constant value

photoelectric emission

the release of electrons from a suitable material when light is shone on it

wave characteristics of protons

they are positively charge it has mass of one they are found at the centre of nucleus

uses of x rays other than medicine

they are used in radios they are used in airport to detect metals and contraband

hazards of over exposure to x rays in a labatory

they cause cancer it can burn the skin they can also destroy body cells and tissues they cause genetic mutations with undesirable hereditary consequences

properties of cathode rays

they cause glass and other materials to fluorescence they throw shadow at the anode end of the tube they are negatively charged a magnetic field deflects the cathode ray they carry considerable energy

observations in support of de broglies assumption that moving particles behave like waves

they have wavelength or frequencies photoelectric effect Compton effect electrons show diffraction patterns

properties of matter which are common to all substances

they occupy space they both have weight there exist intermolecular force between molecules of matter

reasons that show x rays are waves

they travel in straight lines it can be reflected, diffracted and refracted

anode

this is a positive electrode through which electric current enters the electrolyte

electrolysis

this is the chemical decomposition of an ionic compound into molten and aqueous form with the passage of electricity

chain reaction

this is the continuous bombardment of uranium 235 with neutrons which result into the formation of another unstable uranium isotope which quickly disintegrates to yield nuclei

cathode

this is the negative electrode through which current leaves the electrolyte

yield point

this is the point beyond the elastic limit in which the elastic material has yielded all its its elasticity permanently and has become plastic

refraction of wave

this is the process by which a wave undergoes a change in its direction of propagation while passing from one medium to another of different density

uses of polaroids

to study optical properties of metal in converting optical instruments into polarising instruments