light definitions

Question 1

light

Answer 1

light is a form of energy that travels by electromagnetic waves

Question 2

reflection

Answer 2

reflection of light is the ‘bouncing’ of light off surfaces

Question 3

diffuse reflection

Answer 3

diffuse reflection is the way in which light is reflected off an object that one would not normally regard as reflective

Question 4

regular reflection

Answer 4

regular reflection is the way in which light reflects off smooth surfaces like mirrors

Question 5

incident ray

Answer 5

an incident ray is the ray of light falling onto the mirror from an object or light source

Question 6

normal

Answer 6

a normal at the point of incidence is an imaginary line radiating perpendicularly from the mirror at the point where the incident ray strikes the mirror

Question 7

reflected ray

Answer 7

a reflected ray is the ray of light bouncing off the mirror

Question 8

angle of incidence

Answer 8

an angle of incidence is the angle between the normal and the incident ray

Question 9

angle of reflection

Answer 9

an angle of reflection is the angle between the normal and the reflected ray

Question 10

object

Answer 10

an object is what the rays of light have come from directly prior to striking the mirror

Question 11

image

Answer 11

an image is the location from which the rays of light appear to be coming

Question 12

object distance

Answer 12

object distance is the distance between mirror and object

Question 13

parallax

Answer 13

parallax is the relative movement of two objects due to the movement of the observer

Question 14

magnified image

Answer 14

an image is magnified if its height is greater than that of the object

Question 15

diminished image

Answer 15

an image is diminished if its height is less than that of the object

Question 16

inverted image

Answer 16

an image is inverted when it is upside down

Question 17

erect image

Answer 17

an image is erect when it is the same side up

Question 18

image distance

Answer 18

image distance is the distance between mirror and image

Question 19

laterally inverted image

Answer 19

an image is laterally inverted when the right side of the object is on the left side of the image and vice versa

Question 20

real image

Answer 20

a real image is the actual intersection of light rays

Question 21

virtual image

Answer 21

a virtual image is the apparent intersection of light rays

Question 22

pole

Answer 22

the pole of a spherical mirror is the centre point

Question 23

centre of curvature

Answer 23

the centre of curvature of the mirror is the centre of the mirror of the sphere from which the mirror is made

Question 24

principal axis

Answer 24

the principal axis of a spherical mirror is the straight line joining the pole to the centre of curvature

Question 25

focal point/focus

Answer 25

the focus or focal point is the point halfway between the centre of curvature and the pole

Question 26

focal length

Answer 26

the focal length is distance from the distance to the pole

Question 27

refraction of light

Answer 27

refraction of light is the way in which light 'bends' when it passes from one medium to another

Question 28

refractive index

Answer 28

the refractive index of a medium is the ratio of sin i to sin r when the light travels from a vacuum to that medium

Question 29

total internal reflection

Answer 29

total internal reflection is the optical phenomenon where light is reflected back from a boundary between 2 media, it occurs when the light is travelling towards the rarer medium from the denser one, striking the boundary with an angle of incidence greater than the critical angle for those 2 media

Question 30

critical angle

Answer 30

the critical angle is the angle of incidence in the denser medium which causes an angle of refraction of 90 degrees

Question 31

optic centre

Answer 31

the optic centre is the centre point of the lens

Question 32

principal axis

Answer 32

the principal axis of a lens is the straight line passing through the optic centre that enters the lens ar right angles to the face of the lens

Question 33

principal focus

Answer 33

the principal focus/ focus is the point though which light travelling parallel to the principal axis converges to for a convex lens or appears to diverge from a concave lens

Question 34

focal length

Answer 34

the focal length is the distance from the focus to the optic centre

Question 35

power of a lens

Answer 35

the power of a lens is the inverse of the focal length

Question 36

compound lenses

Answer 36

compound lenses are combinations of two or more lenses in contact with each other

Question 37

accommodation

Answer 37

accommodation is the process of adjusting the focal length of the lens to focus distant or near objects on the retina

Question 38

short sightedness

Answer 38

short sightedness means that distant objects cannot be seen clearly

Question 39

long sightedness

Answer 39

long sightedness means that near objects cannot be seen clearly

Question 40

spectrum

Answer 40

the spectrum is the range of wavelengths present in the electromagnetic radiation

Question 41

dispersion

Answer 41

dispersion is the separating out of the different wavelengths of light