Light Flashcards
What are luminous sources
Sources that produce or give out light of their own
How can we see objects which are not luminous?
Light rays hit the object and are reflected into our eyes
Draw diagram of right ray passing through a concave prism and name the type of ray
diverging
Draw a ray passing through a convex prism and describe the ray
converging
What are the three types of rays?
converging >
diverging <
parallel =
Evidence for light travelling in straight lines and phrase used?
shadows
pinhole camera
light in a lazer beam
light streaming through branches
rectilinear propagation
In a pinhole camera the image is:
inverted (upside down), real (formed on a screen)
- In the pinhole camera the image is quite dim, how do you make it brighter and what else will happen?
- What happens if the pinhole is made bigger?
1 Move object closer and image becomes bigger and brighter.
2 Image becomes fuzzy (less clear).
How are shadows formed?
When opaque objects stop light from reaching an area.
Draw a diagram to illustrate a shadow produced from a point source. What is the shadow like and called?
UMBRA - a sharp and completely dark shadow
Draw a diagram to illustrate a shadow produced from an extended light source. What is the shadow like and called?
Umbra and PENUMBRA formed.
Penumbra is dim and not shaped, it is a partial shadow.
What is the law of reflection? Illustrate using a diagram.
Angle of incidence equals the angle of reflection, all angles taken from the normal.
Show how a periscope works
angle of mirrors is 45 degrees
Draw a diagram to illustrate a mirror image.
Make sure to label and show direction of light.
Properties of the image in a plane mirror:
same size, upright, laterally inverted, same distance behind mirror as it is in front.
Draw a diagram to illustrate refraction of light passing through a glass block.
remember to label emergent angle and that it is parallel to the incident angle.
What happens as the light passes into a glass block?
Light ray enters more optically dense medium e.g. air to glass, the ray slows down and bends towards the normal.
When light leaves more optically dense medium e.g. glass to air, the ray speeds up and bends away from the normal.
How are all colours made?
primary colours etc.
How is the colour of an object/filter produced?
Colours not absorbed are reflected.
Show how an object appears when placed in water.
how normal
ilustrate light passing through a glass prism and explain what happens
The different colours of white light are refracted by different amounts as they enter the triangular prism. The change of direction is called DEVIATION. Splitting of colours is called DISPERSION.
