Definitions Flashcards Preview

Physics > Definitions > Flashcards

Flashcards in Definitions Deck (62):
1

Principal of Conservation of Energy

Energy may be transformed from one form into another, but it cannot be created or destroyed

2

Principal of Conservation of mechanical energy

The total amount of mechanical energy which the bodies in a system posses is constant, provided no external forces act

3

Kirchhoff’s first law

At any junction or point of the circuit, the sum of the current going in is equal to the sum of the current going out

Conservation of charge

4

Kirchhoff’s second law

The emf of a circuit is equal to the potential difference in any closed loop of a circuit

Conservation of voltage

5

Ohm’s law

V is proportional to I as on a graph the line would be a straight line through the origin

6

Volt

Energy per unit charge

7

Coulomb

One amp per one second

8

The charge of an electron

1.6*10^-19

9

Charge

A property of protons and electrons equivalent to the product of current and time

10

Potential difference

Work done BY each unit of charge in a component converting electrical energy into other forms of energy

11

Electromotive force

Work done ON each unit of charge in a component converting energy from other forms into electrical energy

12

Resistance

The opposition to the flow of current

13

The ohm

A. Opponent has a resistance of one ohm when a potential difference of one volt is required to push a current of one amp through the component

14

Power

The rate of work done Or the work Done per unit time

15

Kilowatt-hour

The energy used by an appliance with a power rating of 1KW in one hour equivalent to 3.6MJ

16

Electron density

The number of free electrons per unit volume of a conductor

17

Antiphase

When the particles of two waves oscillate in the exact opposite path, when one reaches maximum positive amplitude the other reaches maximum negative amplitude

18

Archimedes’s principle

The upthrust on an object in a fluid is equal to the weight of the fluid it displaces

19

Braking distance

Distance travelled by a vehicle from the time brakes are applied until the vehicle stops

20

Brittle

A property of a material that does not show plastic deformation or become deformed at all when under stress

21

Capacitor

A component that stores charge, consists of two plates separated by an insulator

22

Coherence

Two waves that are coherent have a constant phase difference

23

Constructive interference

Superposition of two waves in phase so that the resultant wave has greater amplitude than the original waves

24

Coulomb

The derived SI unit of electrical charge, 1 coulomb of electric charge passes a point in one second when there is an electric current of one ampere

25

Destructive interference

Superposition of two waves in antiphase so that the waves cancel each other out and the resultant wave has a smaller amplitude than the original wave

26

Diffraction

Waves spreading out as they pass through a gap or around an obstacle and spread out

27

Diode

A semiconductor component that allows current only in one particular direction

28

Displacement

The distance travelled in a particular direction - it is a vector so can have positive and negative values

29

Displacement in waves

The distance from the equilibrium position in a particular direction

30

Drag force

The resistive force exerted by a fluid on an object moving through it

31

Ductile

Property of a material that has a large plastic region in a stress-strain graph

32

Elastic deformation

A reversible change in the shape of an object due to a compressive or tensile force

33

Elastic limit

The value of stress or force beyond which elastic deformation becomes plastic deformation and the material will no longer return to its original shape

34

Elastic potential energy

The energy stored in an object because of its deformation

35

Electrolyte

A liquid containing ions that are free to move and so to conduct electricity

36

Electromagnetic spectrum

The full range of frequencies of electromagnetic waves, from gamma rays to radio waves

37

Electronvolt

A derived unit of energy used for subatomic particles and photons, defined as the energy transferred to it from an electron when it passes through a potential difference of 1 volt

1eV=1.6x10^-19

38

Energy

The capacity for doing work, measured in joules

39

Equilibrium

A body is in equilibrium when the net force and net moment acting in ut are zero

40

Extension

The increase in length of an object when a tensile force is exerted on it

41

Filament lamp

An electrical component containing a narrow filament of wire that transfers electrical energy into heat and light

42

Force constant

A quantity determined by dividing force by extension (or compression) for an object obeying Hooke’s law

43

Free electron

An electron in a metal that is not bound to an atom and is free to move

44

Wave frequency

The number of wavelengths passing a given point per unit time

45

Fundamental frequency

The lowest frequency at which an object can vibrate

46

Gravitational potential energy (g.p.e)

The capacity for doing work as a result of an object’s position in a gravitational field

47

Harmonic

A whole-number multiple of the fundamental frequency

48

Hooke’s law

The force applied is directly proportional to the extension of the of the spring unless the limit of proportionality is exceeded

49

In phase

Particles oscillating perfectly in time with each other reaching maximum positive and negative amplitudes at the same time

50

Interference

Superposition of two progressive waves from coherent sources to produce a resultant wave with a displacement equal to the vector sum of the amplitudes of the two waves

51

Interference pattern

A pattern of constructive and destructive interference formed as waves overlap

52

Internal resistance

The resistance of a source of e.m.f. due to its construction, which causes a loss in energy/voltage as the charge passes through the source

53

Ion

An atom that has either lost or gained electrons so has a net charge

54

Kilowatt-hour

Energy in kWh can be calculated by multiplying the power in law bf the time in hours, it is a derived unit with 1kWh=3.6MJ

55

Kinetic energy

The energy associated with an object as a result of its motion

56

Longitudinal wave

A wave in Which the medium is displaced in the same lines as the direction of energy transfer

57

Mean drift velocity

The average velocity of electrons as they move through a wire

58

Moment

The product of a force and perpendicular distance from a pivot

59

Newton’s first law of motion

A body will remain at rest or continue to move with constant velocity unless acted upon by a resultant force

60

Newton’s second law of motion

The rate of change of momentum of an object is directly proportional to the resultant force and takes place in the direction of the force

61

Newton’s third law of motion

When two objects interact, each everts an equal and opposite force in the other

62

Node

For a stationary wave a point where the amplitude is always zero