Chapter 5 key words

Question 1

angle of incidence

Answer 1

the angle between a ray incident on a surface and the line perpendicular to the surface at the point of incidence, called the normal

Question 2

angle of reflection

Answer 2

the angle made by a reflected ray with a perpendicular to the refracting surface

Question 3

angle of refraction

Answer 3

the angle made by a refracted ray and a line perpendicular to the refracting surface

Question 4

normal

Answer 4

an invisible line perpendicular to the surface at the point of incidence

Question 5

opaque

Answer 5

light does not pass through the surface at the point of incidence

Question 6

translucent

Answer 6

some light gates transmitted, some reflected and some absorbed

Question 7

concave

Answer 7

a surface that caves inwards

Question 8

convex

Answer 8

a surface curving outwards

Question 9

convex lens

Answer 9

a converging lens: thicker at the centre than the edges

Question 10

concave lens

Answer 10

a diverging lens: thinner at the centre than the edges

Question 11

focal length

Answer 11

the distance between the centre or curved mirror and its focus

Question 12

lens

Answer 12

a piece of glass for concentrating or dispersing light rays

Question 13

law of reflection

Answer 13

AOI (i) = AOR (r)

Question 14

Snell’s law (to measure index of refraction)

Answer 14

Question 15

Index of refraction of air

Answer 15

1.00029

Question 16

index of refraction of water at 20 C

Answer 16

1.333

Question 17

index of refraction of glass

Answer 17

1.5 - 1.9

Question 18

index of refraction of diamond

Answer 18

2.42