L04 Reflection

Question 1

Law of reflection

Answer 1

Angle of incidence = reflected angle

Question 2

Specular/regular reflection

Answer 2

• Reflected light leaves surface in a definite beam that follows the Law of Reflection
• Occurs at smooth polished surfaces
• E.g. plane mirror or glass

Question 3

Diffuse / Irregular Reflection

Answer 3

• Incident light is reflected in all directions and does not follow the Law of Reflection
• Occurs at irregular surfaces
• E.g. projection screen or frosted glass

Question 4

Factors affection reflection

Answer 4

Colour, surface, angle of incidence, refractive index of medium

Question 5

Critical angle

Answer 5

• Light travels from high to low index interface (n > n’)

* Incident angle that yields refracted angle of 90o

Question 6

Total internal reflection

Answer 6

• Incident angle greater than critical angle
• Rays are reflected back into same medium as incident ray
• High to low index interface

Question 7

Image form by plane mirror

Answer 7

• Virtual
• Erect
• Same size and shape as object
• Image distance equal to object distance but opposite in sign (l ’ = -l)

Question 8

Image form by curve mirror

Answer 8

• May be real or virtual
• May be erected or inverted
• May be bigger or small
• Maybe nearer or further
• For spherical mirror, object and image focal length is the same.