optics

Question 1

wave theory

Answer 1

light behaves like a wave
frequency speed and wavelength

Question 2

particle theory

Answer 2

light behaves like a particle
discrete packet of energy is a photon
photon travels in straight line

Question 3

huygens principle

Answer 3

wavefronts
light travels outward from a source in wave fashion
wavefronts spread outward circularly in every direction

Question 4

ray

Answer 4

• light is a ray
• rays are straight lines perpendicular ti the wavefront and originates at centre of curvature of wavefronts
• represents direction of travel of wavefronts

Question 5

law of rectilinear propagation

Answer 5

light in a single medium will travel along a straight path called a ray

Question 6

what is ray

Answer 6

direction of travel of wavefront

Question 7

pencil of light

Answer 7

group of rays

Question 8

beam

Answer 8

group of pencils

Question 9

optical medium

Answer 9

• light travels through many materials
• medium is a material that transmits light
• light travels at different speeds through different mediums
• fasted in vacuum

Question 10

visible light

Answer 10

• small section of em spectrum
• 780nm red to 400nm violet
• white light is mixture of wavelengths on visible spectrum
• colour determined by wavelengths reflected from surface

Question 11

speed if light denoted by

Answer 11

c= 3x10power of 8

Question 12

index of refraction

Answer 12

n = speed of light in a vacuum/ speed of light in a material

Question 13

refractive index

Answer 13

always greater than or equal to 1
higher RI the more light is slowed down by a material

Question 14

air RI

Answer 14

1.000

Question 15

water RI

Answer 15

1.333

Question 16

CR39 RI

Answer 16

1.498

Question 17

crown glass RI

Answer 17

1.523

Question 18

polycarbonate RI

Answer 18

1.586

Question 19

convergent rays

Answer 19

come together to meet at a point
always have positive vergence

Question 20

ria

Answer 20

rays travel from left to right
always have an arrow

Question 21

vergence

Answer 21

power of light

Question 22

divergent rays

Answer 22

spread apart from originating point
always have negative vergence

Question 23

parallel rays

Answer 23

never meet
always have zero vergence

Question 24

Vergence L
in diopters D

Answer 24

1 / distance in meters

Question 25

nominal power F total power of front + back surface of lens

Answer 25

F= F1 + F2

Question 26

DS stands for

Answer 26

diopters sphere

Question 27

DC stands for

Answer 27

diopters cylinder

Question 28

electromagnetic radiation

Answer 28

energy emitted and absorbed by charged particles wave-like behavior as it travels through space electric and magnetic components in vauum- travels at speed of light

Question 29

electromagnetic spectrum

Answer 29

- range of all possible frequencies if electromagnetic radiation

Question 30

telescopes

Answer 30

reflecting refracting

Question 31

refracting telescopes

Answer 31

- normal positive and negative lenses

Question 32

refracting telescope gailean

Answer 32

+0 lens and diverging eyepiece main adv- upright image

Question 33

refracting telescope astronomical- kepler-1611

Answer 33

2 + lenses o and e - rays from distance object form a parallel lens at the o lens - o lens forms real primary image in 2nd focal plane - primary image coincides with 1st focal plane of the eyepiece - rays emerge as a parallel pencil and final image seen unaccommodated - eye piece magnifies final image

Question 34

disadvantage of astronomical telescope

Answer 34

can be v heavy inverted image

Question 35

reflecting telescopes adv and disadv

Answer 35

- concave mirror as o lens adv collect more light disadv less weight less defects

Question 36

refracting telescopes eg

Answer 36

astronomical gailean

Question 37

reflecting telescopes eg

Answer 37

newtonian catadioptric

Question 38

f/ratio

Answer 38

ratio of focal length of optical system to the diameter of wits entrance pupil f6 and below- fast f7 to 10- medium f11 and above- slow

Question 39

low f/ ratio

Answer 39

fat brighter image than similar sized telescope with higher f/ ratio

Question 40

radio telescopes

Answer 40

- operate radio frequency portion of EM spectrum

Question 41

infra red in space

Answer 41

where starts are forming and where starlight is absorbed by dust

Question 42

optical in space

Answer 42

where stars are now

Question 43

x ray in space

Answer 43

where stars have died