Y1 Ch 05 Definitions

Question 1

Progessive wave.

Answer 1

A wave that travells through a substance or space, transferring energy.

Question 2

Amplitude

Answer 2

The maximum displacement from the undisturbed position.

Question 3

Wavelength

Answer 3

The distance between peaks.

Question 4

Frquency

Answer 4

The number of cyclea per second

Question 5

Period

Answer 5

The time for one complete cycle.

Question 6

Phase difference

Answer 6

The fraction of a wave cycle between two points along a wave.

Question 7

Longitudinal waves

Answer 7

Particles vibrate parallel to the direction that energy travels in.

Question 8

Transverse waves

Answer 8

Vibrations are at right angles to the direction that energy travels in.

Question 9

Electromagnetic waves

Answer 9

Transverse waves all of which travel at the speed 3*10^8 m/s

Question 10

Mechanical waves

Answer 10

Cannot travel throgh a vacuum, but need a medium to travel through.

Question 11

Polarised wave

Answer 11

When the oscillations of the wave are confined to one plane.

Question 12

Refraction

Answer 12

The change in direction at a boundary when a wave travels from one medium to another.

Question 13

Angle of incidence

Answer 13

The angle between the refracted ray and the normal

Question 14

Angle of refraction

Answer 14

The angle between the refracted ray and the normal.

Question 15

Refractive index

Answer 15

The ratio of a wave’s speed between two materials

Question 16

Total Internal Reflection

Answer 16

The complete reflection of light at a boundary within a material that has a higher refractive index than its surroundings.

Question 17

Critical angle

Answer 17

The angle of refraction for which the angle of incidence is 90 degrees

Question 18

Optic Fibre

Answer 18

A thin glass (or plastic) fibre that transmits light

Question 19

Step index optic fibre

Answer 19

An optic fibre with a uniform refractive index in the core and a smaller uniform refractive index for the cladding

Question 20

Material dispersion

Answer 20

The spreading of a signal caused by the variation of refractive index with wavelength

Question 21

Pulse broadening

Answer 21

When the duration of a pulse increases as a result of dispersion in an optic fibre

Question 22

Modal dispersion

Answer 22

The spreading of a signal caused by rays taking slightly different paths in the fibre

Question 23

Absorption

Answer 23

When energy from a signal is absorbed by the optical fibre