P1.5.2 Reflections

Question 1

What is the normal?

Answer 1

The normal is a construction line perpendicular to the reflecting surface at the point of incidence.

Question 2

What is the ‘law of reflection’?

Answer 2

The law of reflection, which applies to every reflected ray:

Angle of incidence = Angle of Reflection

Question 3

What allows us to see thing?

Answer 3

Reflection of light is what allows us to see things. Light bounces off them into our eyes.

Question 4

What happens when light travelling in the same direction reflects from an uneven surface?

Answer 4

When light travelling in the same direction reflects from an uneven surface such as a piece of paper, the light reflects off at different angles.

Question 5

What happens when light travelling in the same direction reflects from an even surface?

Answer 5

When light travelling in the same direction reflects from an even surface (smooth and shiny, such as a mirror) then it’s all reflected at the same angle and you get a clear reflection.

Question 6

Where is the angle of incidence/reflection on a diagram?

Answer 6

Between the ray itself and the normal.

Question 7

In a ray diagram for an image in a plane mirror, what qualities does the image have?

Answer 7

• The image is the same size as the object.
• It is as far behind the mirror as the object is in front.
• The image is virtual (the object appears to be behind the mirror).
• The image is upright.
• The image is laterally inverted - the light and the right sides are swapped.

Question 8

What steps do you take in producing a ray diagram?

Answer 8

1. Draw the virtual image - it’s the same size as the object and as far behind the mirror as the object is in front.
   (When drawing rays, do a bold line for the rays between the mirror and the eye/object, and a dotted line for the rays between the mirror and the virtual image.)
2. Next draw a reflected ray going from the top of the virtual image to the top of the eye.
3. Now draw the incident ray from the top of the object to the point where the reflected ray meets the mirror.
4. Then repeat steps 2 and 3 for the bottom of the eye - a reflected ray going from the top of the image (same point as previous ray) to the bottom of the eye, then an incident ray from the top of the object (same point as before) to where the second reflected ray meets the mirror.
   (Remember to draw the arrows on the rays)