Light Basics and Materials
In a uniform medium (medium does not change), light travels in what kind of path?
A straight line
What is the law of reflection?
The angle of incidence is equal to the angle of reflection
Why does refraction occur?
It changes speed! (Saying it goes from one medium to another is NOT correct. That is what makes it change speed, and the change of speed is what causes the refraction)
What opening in the eye becomes larger in dim light so that more light can enter?
The pupil
A microscope
A bathroom window allows light through but does not let you clearly see through it. What kind of material is this?
Translucent
What is the name of the imaginary line drawn perpendicular to a reflecting surface?
The normal line
What does a concave lens do to parallel light rays?
The light rays diverge / spread out.
What structure carries electrical impulses from the eye to the brain?
The optic nerve.
What optical device is essentially just two short refracting telescopes side by side.
Binoculars
Approx. how fats does light travel in a vacuum?
~300,000 km/s
Light strikes a rough surface and scatters in many directions. What type of reflection is occuring?
Diffuse Reflection
A convex lens causes incoming light rays to meet at an area we call ____ .
The focal point.
What do the ciliary muscles do when your eye is trying to focus on objects at different distances?
They change the shape of the lens. (Accommodation)
Two photographs of the same size have a dpi of 75 and 300 respectively. Which of the two should contain more detail?
The 300 dpi
Isaac Newton used a prism to make what observation?
That white light is made up of ROYGBIV / all the colours.
What type of mirror might a make up artist use?
Concave mirror - to enlarge the face
What two factors determine how much refraction will occur when light enters a new medium?
1. The speed
2. The angle at which it enters the medium
Why do humans have a blind spot in each eye?
It occurs where the retina meets the optic nerve / where the optic nerve leaves the eye.
What is the major difference between a reflecting telescope and a refracting telescope?
A reflecting telescope uses curved mirrors and a refracting telescope uses lenses.
Pythagoras believed that vision was a result of beams travelling out of the eyeball. What observation showed that this idea cannot be correct?
We cannot see in the dark.
A ray of light strikes a plane mirror at 25 degrees to the MIRROR surface. What is the angle of reflection when measured from the normal.
A person has slightly elongated eyes causing the focal point to be in front of the retina. What type of lens do they need to correct this problem?
A concave lens on their glasses.
Name any one of the three adaptations that help nocturnal animals see in very low light.
1. Large pupils
2. More rods than cones
3. The tapetum lucidum (if you describe this structure I will give it)
A camera and an eye are both trying to focus on a moving object that is coming closer. How does each system adjust to keep the image in focus?
The eyes ciliary muscles change the shape of the lens.
In a camera the lens moves in relation to the film/sensor.