Light Flashcards
Where does the light come from?
luminous sources
Give 5 sources of light.
sun, bulb, candle, fire, lightening
What does the word luminous mean?
emits light
How can we see objects which are not luminous?
The light rays hit the object and are reflected from it into our eyes
What way does light travel and what is it called? Illustrate the different types.
Light travels in straight lines called rays.
Name 2 types of prism/lens
concave prism/lens, convex prism/lens
Draw how light passes through a concave prism and state what type of ray is created.
diverging
Illustrate how light passes through a convex prism and state what type of ray it creates.
converging
Give 5 pieces of evidence for light travelling in straight lines.
- Shadows
- The Pinhole Camera
- Light streaming through water droplets in clouds
- Light coming through the branches in a forest
- Light in the laser beam.
Decribe what a pinhole camera image is and draw a diagram to show how a pinhole camera works.
Image is INVERTED (upside down) and REAL (formed on a screen)
In a pinhole camera:
- Is the image on the screen inverted (upside down) or the right way up?
- Is the image brighter or dimmer that the object?
- Is the image smaller or larger than the object?
- What is the effect on the image of moving the camera close to object?
- inverted (upside down)
- dimmer
- smaller
- gets bigger
In a pinhole camera, if the pinhole is made larger, what happens to the (i) brightness and (ii) sharpness of the image?
(i) brighter, (ii) more blurred
What is the name given to light travelling in straight lines?
RECTILINEAR PROPAGATION
What is the lens in the eye like when looking at a near object
Looking at a near object the lens is fat
What is the lens in the eye like when looking at a far object
Looking at a near object the lens in thin
What happens to the height of an object as the distance of the pinhole camera is increased?
Height of an object is decreased as the distance of the pinhole camera is increased
Light travels in straight lines at a speed of ___________.
300 000 000 m/s
How are shadows created?
Shadows are cast when an opaque object stops light from reaching an area.
Draw a diagram to show how a shadow of a circular object is created with a small light source, describe it.
Between A and B no light reaches the screen.
The shadow is sharp an completely dark.
This type of shadow is called an UMBRA.
What happens if a extended (large) light source is used to create a shadow, illustrate and describe it.
There is an UMBRA and a PENUMBRA
There is an outer region on the screen where all the light can reach.
Between the outer region and the umbra is a ring-shaped region, a partial shadow called the PENUMBRA.
It is dim and not sharp.
What is an eclipse of the (i) moon and (ii) sun called?
(i) lunar eclipse, (ii) solar eclipse
Describe an eclipse of the moon
Describe an eclipse of the sun
