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Flashcards in Definitions Deck (45):
1

Refraction

Change of direction of a wave that occurs when the speed of a wave changes

2

Absolute Refractive Index

The index of refraction of a substance when rays pass into it from a vacuum

3

(Relative) Refractive Index

The ratio of the velocity of light in two different media

4

Critical Angle

The angle of incidence beyond which rays passing though a less medium to the surface of a more dense medium are totally reflected

5

Fibre optic cables

Cables that transmit information by total internal reflection

6

Cladding

A covering or coating on a structure or material

7

Total Internal Reflection

Complete replication of light reaching a medium change when the angle of incidence > critical angle

8

Work Function of a metal

The minimum amount of energy required to release an electron from the surface of a metal

9

Doppler Effect


Change in frequency as a source of a wave moves relative to its source.



Therefore, as v=fλ, whilst frequency increases and wavelength decreases, velocity emmited from the source will stay constant.


10

Polarising Filter

A photographic or optic filter that polarises light through it

11

Polarisation

Process in which waves are restricted to certain directions of vibrations.

12

Specific Rotation

Angle through which plane polarised light is rotated.

13

Emf

Electromotive force. The p.d across the terminals when no current flows. Energy per unit charge by the source.

14

Voltage (p.d)

Energy converted per unit charge

15

Internal Resistance

Resistance that occurs in the cell(s) of a circuit

16

Load

Component or partition in a circuit that consumes electrical power.

17

Current

The rate of flow of charge. I=Q/t

18

Potential divider

Device that consists of two resistors. This divides the voltage across the resistors.

19

Potentiometer

Instrument that measures the emf by balancing it agains the p.d produced by a known current and though a known variable resistance.

20

Diode

Electrical component with asymmetric conduction; low resistance one way but high the other way

21

Diode

Electrical component with asymmetric conduction; low resistance one way but high the other way

22

Equation for refractive index

sin(I)/sin(r)

23

Equation for the efficiency of an electrical power output

%efficiency = [(useful energy output)/(total energy input)]

24

What is the order, from highest frequency to lowest, of the main types of electromagnetic waves?



 


Q image thumb

G, X, U, V, I, M, R


A image thumb
25

Semi conductor

Substance that has a conductivity between that of an isolator and that of a typical conductor such as a normal metal

26

Negative temperature coefficient (NTC)

Resistance (or other value) decreases when temperature increases

27

Positive temperature coefficient (PTC)

A value that increases when temperature increases

28

Drift velocity

Average velocity of the electrons flowing

29

Free electrons

Electrons free to move and carry charge

30

Resistors in parallel

1/Rt = 1/R1 + 1/R2 ......

31

Resistors in series

Rt = R1 + R2.....

32

Resistance

Voltage / Current

33

Resistivity

Resistance x Area / Length

34

De Broglie's wavelength

Mv = h / wavelength

35

Plank's constant

6.63 x10-34

36

Wave- particle duality

The concept that photons and electrons exhibit the properties of both waves and particles

37

Photo electric effect

The fact that photons with enough energy can transfer energy to electrons in metal to allow them to escape

38

Intensity

The measure of energy in a wave

39

Power

Work done per unit time

40

Photon

A particle representing a quatum of light

41

Line sprectra

An emission spectrum consisting of separate lines

42

Work function

The energy needed for an electron to escape the metal surface

43

Threshold frequency

The minimum frequeny of light for photoelectrons to be emitted from a metal

44

Diffraction grating

An optic component that splits and diffracts light into several beams

45

Stopping voltage

The voltage at which no electrons have enough kinetic energy to overcome