Chapter 6 Flashcards
What are the basic components of the human eye?
Pupil, lens, and retina.
What does the pupil do?
Controls how much light enters the eye.
What happens to the pupil in low light?
It dilates (opens wider).
What is the role of the lens in the eye?
Bends light to form an image on the retina.
What is the retina?
Contains light-sensitive cells (cones and rods).
What do the light-sensitive cells in the retina do?
Send signals to the brain via the optic nerve when triggered by light.
What is refraction?
The bending of light as it passes from one medium to another (e.g., from air to glass).
Why does light bend when it enters glass at an angle?
Light travels more slowly through denser matter.
What is the focus (or focal point)?
The point where parallel rays of light converge after passing through a lens.
What is the focal plane?
The place where the image appears in focus.
Is the image formed by the lens of the eye right-side-up or upside-down?
Upside-down.
What are the main components of a camera?
An opening for light (like a pupil), a lens, and a detector.
What is the purpose of the shutter in a camera?
To control the exposure time.
What is exposure time?
The amount of time during which light collects on the detector.
What are pixels?
Picture elements on an electronic chip that record light in a camera.
How do pixels work?
When a photon strikes a pixel, it causes a bit of electric charge to accumulate.
What is image processing?
Techniques used to combine and manipulate images.
What are some uses of image processing in science?
- Sharpening images
- Adjusting colors
- Correcting exposure
- Removing artifacts
What is the main purpose of a telescope?
To collect more light than our eyes can.
How much more light can a large telescope collect compared to the human eye?
Can collect more than 1 million times more light.
What is angular resolution?
The smallest angle over which we can tell that two dots (or stars) are distinct.
What is the angular resolution of the human eye?
About 1 arcminute (1/60 of a degree).
Define angular separation.
The angle that appears to separate two objects in the sky.
How does distance affect angular separation?
Objects that are further away have smaller angular separation.
What part of the eye does the lens work together with?
The cornea.
What makes the sun look squashed at sunset?
Light from the lower portion of the sun passes through more atmosphere and bends slightly more than light from the upper portion.
What is overexposure?
So many photons collect that they can no longer be counted accurately.
What happens after an exposure is complete in a digital camera?
A computer measures the total electric charge in each pixel, thereby determining how many photons have struck each one.
What does each ray represent when visualizing the bending of light?
A series of light waves coming from a single direction.
What happens to light rays that pass directly through the center of the lens?
They are not bent at all.
