Refraction

Question 1

Refractive index of semi-circular block of material PRACTICAL

Answer 1

• draw around block
• shine ray of light towards centre of the straight edge of the block
• use pencil + ruler to mark positions of incident ray and refracted ray
• remove block
• draw normal where he ray was incident on block
• measure angle of incidence + refraction
• calculate refractive index (n = sini / sinr)
• plot graph of sini against sinr…
• use gradient to find n

Question 2

Define critical angle

Answer 2

• angle of incidence in the more dense medium for which the angle of refraction is 90 degrees in the less dense medium

Question 3

Define total internal reflection

Answer 3

• when light travels from more dense to less dense medium…
• but angle of incidence > critical angle…
• so all light is reflected back into more dense medium

Question 4

Define refraction

Answer 4

• when a wave passes through a boundary between two different transparent media (of different optical densities)…
• resulting in a change of direction…
• due to a change in wave speed

Question 5

Define reflection

Answer 5

• when a wave hits a boundary but does not pass through…
• and remains in the original medium

(For light angle of incidence = angle of reflection)