Physics Definition List

Physics Definition

Kinetic Model Of Matter: Transfer of Thermal Ther mal Energy : Brownian Motion Brownian Motion is th the e movement of smoke partic par ticles les in a ra rando ndom m and cont co ntin inuo uous us mo moti tion on in al alll direction. Conclusion: Provide Evidence that air molecules are al alway ways s in con contin tinuou uous s and random motion. Temperature: It is th the e me meas asur ure e of the deg egrree of ho hottne nes ss of a body. Heat refers to the amount of the therm rmal al ene energy rgy that is contained in a body. Lower-fix Lowerfixed ed poi point nt aka Ice Point: Temperature of pure melt me ltin ing g ic ice e at st stan anda dard rd atmospheric pressure. Upper-fixed point aka steam point: Temperature of steam from boilin boi ling g wat water er at sta standa ndard rd atmospheric pressure.

Specific heat capacity( capacity(c ): ): Is the amount of heat required to raise the temper tem perat ature ure of 1kg of the object by 1oc

Conduction is the process by which heat is transferred throug thr ough h a med medium ium by the collisions of one particle to another.

Q = mcθ 

Convection is the proc process ess by which heat is transmitted from one plac place e to another by the movement of heated particles in a gas or liquid.

Melting is the process process in which a substance changes from a solid state to a liquid stat st ate e wi with thou outt a ch chan ange ge in temperature.

Radiation is the process of  heatt tra hea transf nsfer er thr throug ough h the emissi emi ssion on or ab absor sorpti ption on of  electromagnetic electromagnet ic waves Therm Ther mal Prope perrti ties es Matt Ma tter er : Energy = power x time

of 

Latent heat of fusi Latent fusion on (lf ) of a substance is the quantity of heat needed to change a unit mass of the subs su bsta tanc nce e fr from om so soli lid d to liquid liqui d with without out a chang change e in temperature.

Internal Ener Internal Energy gy is the sum of kinet kinetic ic energy and potentia pote ntiall energ energy y of all the particles. Heat Capa Capacity city((C ) is the amount of heat required to raise the temperature of the object by 1oc.

C  =

Boiling is th the e pr proc oces ess s in which a substance changes from fr om a li liqu quid id st stat ate e to a gase ga seou ous s st stat ate e wi with thou outt a change in temperature.

Q =ml 

 f  

Q

θ  -1-

Latent heat of vapo Latent vaporiza rization tion (lv): of a sub subst stanc ance e is the quantity of heat needed to change a unit mass of the substance from liquid to gas without a change in temperature.

Q =ml 

v

Light: Law 1: The angle of   incidence is = to the angle of reflection. Law2:: Th Law2 The e in inci cide dent nt ra ray, y, reflec ref lected ted ray and nor normal mal lies at the point of incidence all lie on the same plane. Refraction: The bending of  Refraction: light lig ht whe when n it pa passe sses s fro from m one transparent medium to another. Law1: Th Law1: The e in inci cide dent nt ra ray, y, refrac ref racted ted ra ray y and nor norma mall the point of incidence all lie on the same plane Law2:: For 2 given media, Law2

Physics Definition

n=

sin i sin r 

(Less

dense

to

denser medium)

n=

sin r  sin i

(Den (D ens ser

to

les le ss

dense medium) (n= ref efra rac ctiv ive e in ind dex or optical density) Refractive index of medium:

n

=

c v

C= speed of light 3x108 V= velocity of light

2. An Angl gle e of in inci cide denc nce e (i ) mustt be gr mus great eater er tha than n the critical angle( c ). ). Thin converging lenses:

sin c =

1 n

Conditions for TIR: 1. Light must travel from an opti op tica call lly y de dens nser er me medi dium um into in to op opti tica call lly y le less ss de dens nse e medium

Wavelength ( λ  ): dis isttan ance ce bet etw wee een n 2 identical points on successive waves.

Focal len Focal length gth F  is the distance between the optical cent ce nter er of th the e le lens ns to the focal point

Frequency (f ): no of   comple com plete te wav wave e in one second.

Linear magnification ( m) is th the e ra rati tio o of th the e im imag age e height hei ght (hi) to th the e ob obje ject ct height (ho).

m=

Total internal reflection: Critical Criti cal ang angle( le(c ): is the angle of incidence for which the ang angle le of ref refrac racti tion on in the optically dense medium is 90o.

Amplitude (a): Maximum Maxi mum disp displace lacement ment of wave from rest position.

Period (T ): ): time taken to generate gener ate one comp complete lete wave.

hi ho

T  =

(Or the image distance ( v ) from the lens to the object distance (u) from the lens)

 f  

Speed of wave: Distance moved by any point on the wave in one second.

v m

1

=

Hence,

λ  v = f  λ 

u

Transverse wave: wave: are wave s in which the directio dire ction n of vibr vibrati ation on is perp pe rpen endi dicu cula larr to the th e direction of wave motion.

General Wave Properties: Wave: Pheno Wave: Phenomeno menon n which energy is transferred through vibrations.

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Longitud Longi tudina inall waves wav es:: are waves in which the directio dire ction n of vibr vibratio ation n of  the th e wa wave ve pa part rtic icle les s is parallel para llel to the direc direction tion of wave motion. Wave fron frontt: imaginary line on a wave that joins all points which have the same phase of vibration. Sound: Compressions : region wher wh ere e ai airr pa part rtic icle les s is slig sl ight htly ly high hi gher er than th an norm no rmal al atmo at mosp sphe heri ric c pressure. Rarefaction: Rarefaction: region wher wh ere e ai airr pa part rtic icle les s is sligh tl tly lower than norm no rmal al atmo at mosp sphe heri ric c pressure. Echo: re Echo: refl flec ecte ted d so soun und d wave wa ve fr from om la larg rge e an and d hard surface. Loudness : Loudness: depe de pend nden entt on amplitude. Pitch: dep Pitch: epen ende dent nt on frequency of the wave

Physics Definition

Ultrasound are sound that are above the upper hearing limit of the human ear.

Acceleration (a) is the rate of change of   velocity with time.

Kinematics:

a=

Scalar:  units  magnitude  no direction

Distance (d ) tot total al len length gth covered by a moving object. the in a

Speed is the rate of change of distance with time.

Speed  =

Area under graph equals to distance travelled. In gene ge nera ral, l, aver av erag age e spee sp eed d is al alwa ways ys ar area ea under und er gra graph ph div divide ide by time. Average speed=

The Dow Downwa nward rd force force is equa eq uall to th the e up upwa ward rd forrce, hen fo ence ce no ne nett force.

area.under.graph graph

Distance-time graph: Gradient: Gradient: object.

speed

t  of  

If it is a straight line, it is travelling at a constant speed.

d  t 

Velocity (v ) is the rate of  change of displacement with time.

Velocity =

t 

Terminal Velocity: Velocity: When an object falls at a constant maximum velocity, with an acceleration of 0m/s2, it is kn know own n as te term rmin inal al velocity.

Vector: direction  units  no magnitude

Displacement( s) dist di stan ance ce me meas asur ured ed specific direction.

v −u

VelocityVeloci ty-ti time/ me/ time graph:

Gradient give gi ves s the acceleration. Positive gradient: acceleration. Neg Ne gativ ive e gra gr adi dien entt: Deceleration or retardation. Zero gradient: (i) object at rest (ii) moving at constant speed

Whe hen n acc ccel eler erat atiion constant in graph,

average.speed

=

1 2

is

(v + u )

v =

Final velocity u=Initial velocity t = time taken change

speedspe ed-

 s t  -3-

for

Dynamics: Newton 1st Law Law:: When there is no net force acting on a body, the body will wi ll re rema main in at re rest st an and d a body in motion will continue its mot otio ion n at co con nst sta ant velocity. Newton 2nd Law Law:: Net force action on a body is di direc rectl tly y pro propor porti tiona onall to the product of the object’s object’s mass and the acceleration it produces. Resultant/net force:

FR=ma Resultant Result ant for force ce pr produ oduces ces acceleration n et constant force=constant acceleration. doub ubli ling ng ne nett fo forc rce e wi will ll do double acceleration produce Doubling mass requires a forrce twi fo wice ce as lar arg ge to achieve the same acceleration.

Physics Definition

Newton 3rd Law Law:: For every action, there is an equal and opposite reaction, and they act on di diffe fferen rentt bodies.

Density is the the ma mass ss pe perr unit volume of a substance.

Inertia is the reluctance of  a body to change its state of rest or motion. Or It is the tendency of a body to remain at rest, or continue moving at a constant speed.

Turning Effect of Forces

Friction is a fo forrce tha hatt opposes motion. Mass, Weight & Density: Mass is a measure of the amou am ount nt of ma matt tter er in an object obj ect.. SI uni unit: t: kil kilogr ogram am (kg)

 ρ  =

M 

Work, Energy & Power:

V 

Work done by a force is the product of force applied and the distance moved in the direction of the force.

Moment of force is the product of the force, and the perpendicular distance from the line of action of  the force to the pivot.

Moment

=

W .D = F  x d  Energy is defined as the capacity to do work.

Fx ⊥ d  

Centre of gravity of an object is the point where the whole weight of the object seems to act on.

Gravitational field strength (g (g)) is de defi fine ne as the th e grav gr avit itat atio iona nall forc fo rce e acting act ing per uni unitt ma mass ss of a body.

Stability is a measure of a body’s ability to regain its original position

 P  =

W .D

K. E. =

1 2

mv2

G.P.E is the energy a body possesses due to its position from the surface of  the earth.

G.P.E. = mgh The principle of the conservation of energy states that Energy can neither be created nor destroyed in any process. It can be converted from one form to another or transferred from one body

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t 

or  P  =

 E  t 

Pressure is the force acting per unit area on a body.

 P  =

 F   A

Pressure due to liquid: liquid :

P = h ρ  g  

K.E is the energy possesses due to its motion.

Principle of moments states that when a body is in equilibrium, the total clockwise moments about the pivot = to the total anticlockwise moment about the same pivot.

Weight is due to the pull of  gravit gra vity y (or (or,, gra gravit vitati ationa onall force forc e of attr attracti action) on) upon a mass.

to another but the total amount remains constant. Power is the rate of work done or energy converted.

Atmospheric pressure is the weight exerted by the atmosphere. Output force in a hydraulic system=

 F B

  A   = F A   B     A A  

A barometer is an instrument used for measuring atmospheric pressure.

Physics Definition

Static Electricity Electric Field is the region where an electric charge experiences an electric force. Magnetism Magnetic Field is the region around a magnet in which a magnetic force can be detected by a magnetic material. Electricity Charge is measured in coulombs (C) Charge of one electron is -1.6x1018 . Current is the rate of flow of charge that flows through any particular point.

 I  =

Q

V  =

Potential Divider divides voltage proportionally into 2 voltages.

W 

V2

Q

VT 

Resistance is the ratio of  the potential difference across the component to the current flowing though it.

W  Q

=

IR2 I ( R1 + R2 )

Earth Wire is used for safety reasons. Connected to metal casing of an appliance and direct excess currents due to the ground when there is a leakage or a short circuit.

RI = V   Power of an electrical component is the product of  the current flowing through it and the potential difference across it.

Fuse melts when excess current flows through it breaking the circuit to prevent current from flowing to prevent user from electrocution and also prevent damage to appliance.

P= IV   Ohm’s Law states that the current passing through a conductor is directly proportionall to the potential proportiona difference between its ends provided that the physical conditions and temperature remains constant.

Electromagnetism/ Electromagnetic Electromagneti c Induction Permanent Magnet: Magnet: provide strong magnetic field. Curved in to provide radial field.

t 

E.m.f is defined as the work E.m.f is done by a force in driving a unit charge around a complete circuit.

ε  =

Voltage is the work done to drive a unit charge through the component.

Diode only allows current to flow in one direction Rectification is the process of converting alternating current to a direct current usually through the use of a diode.

Carbon Brushes: Provide electrical contact between circuit and coil

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Soft Iron Core: Core : to concentrate magnetic field lines around the coil to exert a greater force on the coil. (D.C motor)Split ring commutator: Reverses the direction of current flowing into the coil for every half a turn to ensure the coil rotates in one direction. (A.C motor)Slip ring: Reverse direction of induced current flowing in the coil for every half a rotation. Why transformer need A.C? It is to provide a constantly changing magnetic field for electromagnetic electromagneti c induction. Hence a constantly changing current is required.