light 1.1

Question 1

define light

Answer 1

form of energy that travels in straight lines in the form of beams and rays

Question 2

define a ray of light

Answer 2

direction or path along which light energy travels in a medium

Question 3

define a beam of light

Answer 3

a group of light rays

Question 4

name 3 types of light beams

Answer 4

parallel
convergent
divergent

Question 5

list four evidences of the principle that light travels in a straight line

Answer 5

1. sunbeam through clouds trees windows curtains
2. existence of shadows
3. pinhole camera
4. light from a cinema projector and car headlamp

Question 6

list the two sources of light

Answer 6

luminous - produce their own light like sun and lightbulb
non luminous - do not produce their own light but reflect like humans and moons

Question 7

how do luminous objects produce their own light

Answer 7

radiate light when their atoms become excited when receiving energy
electricity in lightbulbs

Question 8

how are beams visible

Answer 8

dust particles in the air reflect light into our eyes

Question 9

define shadow

Answer 9

dark area/shape produced by an object/body coming in between the rays of light and surface
opaque objects block all light from passing through them and thus creates an area of darkness on the opposite side of the object

Question 10

list 2 reasons for the existence of shadows

Answer 10

opaque objects do not allow light to pass through them
principle that light travels in a straight line

if light did not travel in a straight line would simply curve around the object and no area of darkness/shadow created

Question 11

define umbra

Answer 11

central dark region where no light reaches the surface because rays of light have a concentrated area to beam and therefore a sharp shadow is created

Question 12

define penumbra

Answer 12

partial dark region where some light reaches the surface and a lighter shadow is created because rays are free to extend and therefore a lighter shadow is created

Question 13

define a solar eclipse

Answer 13

the moon casts a shadow onto earth
sometimes when in orbit, the moon comes between the earth and the sun blocking light of the sun from reaching causing an eclipse of the sun

Question 14

define a lunar eclipse

Answer 14

earth obstructs the sun’s light hitting the moon meaning eclipse takes place during the night and when there is a full moon
moon appears reddish in colour because atmosphere absorbs other colours of light while it bends some sunlight towards the moon
moon appears as different colours due to the angle the light hits it at

Question 15

define a pinhole camera

Answer 15

small camera without a lens with a small single aperture or hole
light reflected off of an object passes through and projects on opposite side of the box where photographic film is located

Question 16

if the pinhole camera were made longer what would happen

Answer 16

the shape of the image would be bigger but the brightness would be duller

Question 17

if multiple holes in the pinhole camera were created what would happen

Answer 17

each hole would have their own image which would overlap causing the final image to be blurrry

Question 18

if a bigger hole in the pinhole camera were made what would happen

Answer 18

the image would be blurry as too much light would enter