Reflection

Question 1

Difference between specular and diffuse reflections

Answer 1

Specular - reflections that occur at a smooth, flat surface. Eg, a mirror

Diffuse - reflections that occur at a rough, uneven surface so the light is scattered. Produces distorted image or no image at all. Eg, on rippling water

Question 2

Define:

Incident ray

Reflected ray

Normal

Answer 2

Incident ray: the ray of light hitting the reflective surface.

Reflected ray: the ray of light leaving the reflective surface

Normal: At point of incidence (ray hits mirror) a line perpendicular to the surface is the normal.

Question 3

Laws of Reflection

Answer 3

Law 1: The angle of incidence equals the angle of reflection (i = i’)

Law 2: incident, normal and reflection are in the same plane.

Law 3: Incident and reflected rays sit on different sides of the normal

Question 4

Characteristics of an image formed by a plane mirror

Answer 4

Image:

object distance = image distance
object size = image size
same orientation as object
virtual (cannot be formed on a screen)
laterally inverted

Question 5

Relationship between angle of rotation of a mirror and angle of rotation of reflected ray

Answer 5

The reflected ray is rotated through twice the angle of rotation of the mirror

Eg, mirror rotated 10 degrees, reflected ray rotated 2x10 degrees

Question 6

Describe convex and concave mirrors

Answer 6

Convex mirrors bulge forward and diverge the light (opposite to convex lenses). Negative effect with a plus radius of curvature

Concave mirrors recess inwards and converges light (opposite to a concave lenses). Positive effect with a negative radius of curvature.

Question 7

Define (of a curved mirror):

Pole

Centre of curvature

Principle axis

Radius of curvature

Answer 7

Pole - The centre of a curved mirror

Centre of curvature - Centre of curvature of a curved mirror is the centre of the hollow sphere of which the mirror is apart of

Principle axis - The straight line that passing through the centre of curvature and pole of a curved mirror

Radius of curvature - The radius of the hollow sphere of glass of which the mirror is a part.

Question 8

Define (of concave and convex mirrors):

Principle focus

Focal length

Answer 8

Principle focus - point on the principle axis where the once parallel rays come to focus after being reflected

Focal Length - the distance between the pole and the principle focus