P3.2 - Light + Lenses

Question 1

the reflected image and object ko characteristics [3]

Answer 1

-same size
-same distance from mirror
-laterally inverted

Question 2

refraction

Answer 2

change in direction of a light ray passing form one medium to another / bending of light as it travels from 1 medium to another

Question 3

refractive index

Answer 3

ratio of the speeds of a wave in 2 different regions

Question 4

formula for refractive index (sin)

Answer 4

sin i / sin r

Question 5

critical angle

Answer 5

angle of incidence at which the angle of refraction is 90 degrees and above which all light is totally internally reflected

Question 6

total internal reflection

Answer 6

when angle of incidence in denser medium is larger than the critical angle and the ray gets completely internally reflected (it follows all the laws of reflection)

Question 7

4 characterstics of a formed image (due to lens)

Answer 7

-enlarged / same size / smaller
-diminished and upright / inverted
-virtual and real
-where (in relation to F and 2F)

Question 8

principle axis

Answer 8

line passing through the center of the lens and perpendicular to the axis of the lens

Question 9

principal focus (focal point / focus) (F)

Answer 9

point where parallel rays coming from distant object get converged / focused (meet) after they pass through the lens

Question 10

focal length

Answer 10

distance from the center of the lens to the principle focus (F)

Question 11

formula for sin critical angle

Answer 11

1 / refractive index

Question 12

real image

Answer 12

created by rays in a diagram actually meeting (on the other side of the lens from where object is) and so can be projected onto a screen

Question 13

virtual image

Answer 13

created by imaginary rays in a diagram meeting and so can’t be projected onto a screen (rays diverge so they meet behind object and image is magnified and formed behind object)

Question 14

what happens when rays in a ray diagram are parallel?

Answer 14

they meet at infinity

Question 15

Snell’s Law

Answer 15

when light is refracted, angle of incidence and angle of refraction (sins) are always in proportion

Question 16

formula for refractive index (speed of light)

Answer 16

speed of light in vacuum (3 x 10^8) / speed of light in medium

Question 17

how fast does light travel in a denser medium?

Answer 17

slower

Question 18

what happens to the bending of light and speed of light if the refractive index is high?

Answer 18

bending effect is greater, light slows down

Question 19

what is dispersion of light

Answer 19

refraction of white light (to ROYGBIV) by a glass prism

Question 20

what colour has the highest frequency

Answer 20

violet

Question 21

what colour has the longest wavelength

Answer 21

red

Question 22

when ray leaves, its parallel to what? (refraction)

Answer 22

incident ray

Question 23

formula for speed (frequency and wavelength)

Answer 23

speed = frequency x wavelength

Question 24

diffraction

Answer 24

bending around (scattering) of waves as they pass through a narrow gap or obstacle when wavelength is comparible (matching) to the gap

Question 25

when is diffraction effect the maximum?

Answer 25

when the gap is comparible to the wavelength (same size)

Question 26

wavefront

Answer 26

imaginary line drawn perpendicular to the crest / trough

Question 27

optical density

Answer 27

how much a material is able to slow down light

Question 28

does frequency change when medium changes?

Answer 28

no

Question 29

what happens to ray when going from rarer –> denser (speed + direction)

Answer 29

slower + bends / refracts towards the normal

Question 30

what happens to ray when going from denser –> rarer (speed + direction)

Answer 30

faster + bends / refracts away from normal

Question 31

reflection

Answer 31

wave bouncing off a plane surface (wall / mirror / interface between 2 substances)

Question 32

where does the incident ray, reflected ray, and normal all lie?

Answer 32

same plane

Question 33

what happens to light on a rough surface?

Answer 33

scattering of light wave (light goes in all direction)

Question 34

plane surface

Answer 34

flat at the point at which the wave interacts with the material

Question 35

what causes refraction of light?

Answer 35

density

Question 36

what is wavelength (wavefront)

Answer 36

distance between 2 wavefronts

Question 37

when a ray leaves from denser –> medium, which way does the ray bend?

Answer 37

away from the normal