Light

Question 1

second law of reflection

Answer 1

angle of incidence i is equal to angle of reflection r (i=r)

Question 2

normal in reflection

Answer 2

perpendicular line to reflecting surface of point of incidence

Question 3

angle of incidence

Answer 3

angle between incident ray and normal

Question 4

angle of reflection

Answer 4

angle between reflected ray and normal

Question 5

refraction is meant by

Answer 5

the bending of light as it passes from one optical medium to another

Question 6

normal in refraction

Answer 6

perpendicular line to medium interface (air-water interface)

Question 7

angle of refraction

Answer 7

angle between normal and refracted ray

Question 8

point of incidence in refraction

Answer 8

point at which an incident ray strikes surface

Question 9

what is meant by refractive index?

Answer 9

ratio of speed of light in vacuum to speed of light in medium

Question 10

refractive index for speed

Answer 10

c/v

Question 11

refractive index for angle

Answer 11

sin i/sin r

Question 12

when does total internal reflection occur?

Answer 12

• when light is travelling from optically denser medium to optically less dense medium
• angle of incidence in optically denser medium must be larger than critical angle

Question 13

critical angle definition

Answer 13

the angle of incidence in an optically denser medium for which the angle of refraction in the less dense medium is 90.

Question 14

focal length

Answer 14

the distance between optical centre and focal point