Light and electromagnetic spectrum - SP5

Question 1

what does the letter ‘i’ represent on a ray diagram?

Answer 1

angle of incidence

Question 2

what does the letter ‘r’ represent on a ray diagram?

Answer 2

angle of refraction/reflection

Question 3

what does a ray diagram represent?

Answer 3

it models what happens when light is reflected/refracted

Question 4

what is the normal on a ray diagram?

Answer 4

line drawn at a right angle to the barrier/mirror - this is the line that angles of incidence/refraction/reflection are taken from

Question 5

what is the law of reflection?

Answer 5

when a wave is reflected - the angle of reflection is equal to the angle of incidence

Question 6

what is total internal reflection?

Answer 6

when the angle of incidence increases so much so that it reaches critical angle - the light is completely reflected inside the glass

Question 7

what is the angle of incidence at total internal reflection called?

Answer 7

crictical angle

Question 8

which way does the light ray bend if it goes into amedium where it travels slower?

Answer 8

towards the normal

Question 9

what direction does the light ray bend if the light ray enters a medium where it travels faster?

Answer 9

away from the normal

Question 10

how do we see luminous objects vs non-luminous?

Answer 10

luminous - light from them enters our eyes
non-luminous - they reflect light

Question 11

what is it called when rough surfaces scatter reflected light in all directions?

Answer 11

diffuse reflection

Question 12

what is white light and how can it be split up into the visible spectrum?

Answer 12

white light - a mixture od different colours of light that our eyes see as white
can be split into visible spectum using a prism

Question 13

absorbtion and refkection? what aboute white?

how do we percieve colour?

Answer 13

white light hits a coloured surface - some colours are absorbed, some are reflected. The colour it is presented as is reflected and so, reaches our eyes - all other colours are absorbed - white objects reflect all colours

Question 14

what is a filter and how does it produce coloured light

Answer 14

peice of transparent material that absorbs some colours in white light but transmits (allws through) others

Question 15

how many types of cone cells do we have that detect light? what 3 colours do the cones detect? - if all are present what is percieved?

Answer 15

3 cone types - red, blue or green - (all present shows white)

Question 16

what is a lens?

Answer 16

peice of transparent material shaped to refract light in particular ways

Question 17

what does the power of a lense describe?

what effect do powerful lenses have?

Answer 17

how much it bends light that passes through it - powerful lenses are more curved and hence bend light more

Question 18

what shape is a converging lense and what does it do?

Answer 18

fatter in the middle than the edges - makes parallel rays of light converge at the focal point - narrows the light to a point

Question 19

what is the focal length?

Answer 19

distance between focal point and the centre of the lens

Question 20

what shape is a diverging lens and what does it do?

Answer 20

thinner in the middle than at the edges - spreads out parallel rays

Question 21

what are the uses of a converging lense?

Answer 21

• used to focus rays of light onto a screen to form a reduced real image of a distant object
• used to focus rays of light to form a magnified virtual image of a near object

Question 22

when can real images be formed only?

Answer 22

when rays of light come together

Question 23

what type of wave is light?

Answer 23

electromagnetic

Question 24

how are different frequencies of light percieved by our eyes?

Answer 24

as visible light

Question 25

what are frequencies that are higher than visible light called?

Answer 25

ultra violet

Question 26

what type of wave are all electromagnetic waves?

Answer 26

transverse

Question 27

what speed do electromagnetic waves travel in a vacum?

Answer 27

3x10(8) m/s

Question 28

what do electromagnetic waves do to get light to an observer?

Answer 28

transfer energy from a source