Optics and Human Eye: Mirrors, Lenses, and Vision Correction | Quizlet
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89 Terms
What is the difference between a concave and convex mirror?
A concave mirror curves inward, while a convex mirror curves outward.
What is the centre of curvature (C)?
The centre of the sphere whose surface forms the mirror.
What is the principal axis?
The line through the centre of curvature and midpoint of the mirror.
What is the vertex (V)?
The point where the principal axis meets the mirror.
What is the focus (F) of a concave mirror?
The point where rays parallel to the principal axis meet after reflection.
What happens when an incident ray is parallel to the principal axis in a concave mirror?
The reflected ray passes through the focus.
What happens when a ray passes through the focus of a concave mirror?
The reflected ray becomes parallel to the principal axis.
What happens when a ray passes through the centre of curvature in a concave mirror?
It reflects back upon itself.
What happens when a ray hits the vertex of a concave mirror?
It reflects according to the law of reflection.
What is the law of reflection?
Angle of incidence = angle of reflection.
Where are the focus and centre of curvature in a convex mirror?
Behind the mirror.
What happens to rays reflected from a convex mirror?
They always diverge.
What kind of image does a convex mirror always form?
Virtual, upright, and smaller.
Why are convex mirrors used on car side mirrors?
They provide a wider field of view and reduce blind spots.
What does SALT stand for?
Size, Attitude, Location, Type.
What is the SALT for an object inside the focus of a concave mirror?
Larger, upright, behind the mirror, virtual.
What happens when an object is at the focus of a concave mirror?
No clear image forms because reflected rays are parallel.
Why do flashlights use concave mirrors?
To create parallel reflected rays and form a focused beam.
Why are satellite dishes concave?
They converge incoming waves to the focus where the receiver is located.
What type of mirror is used in makeup mirrors?
Concave mirrors.
What are the 3 laws of reflection?
1. Angle of incidence = angle of reflection; 2. Incident ray, reflected ray, and normal lie on the same plane; 3. Rays traveling along the normal reflect straight back.
How does light travel?
In straight lines.
What is refraction?
The bending of light as it enters a different medium due to a change in speed.
What is the equation for index of refraction?
n = c/v.
What happens to light as index of refraction increases?
Light slows down and bends closer to the normal.
What is the index of refraction of air?
1.00.
What is the index of refraction of water?
1.33.
What is the index of refraction of diamond?
2.42.
What is the critical angle?
The angle of incidence that produces a refracted ray at 90°.
What is total internal reflection?
Complete reflection of light back into the medium.
When does total internal reflection occur?
When light travels from a denser to less dense medium and the angle of incidence is greater than the critical angle.
Why do diamonds sparkle?
Because they have a high refractive index and undergo total internal reflection many times.
Why does an object underwater appear closer?
Refraction bends light rays, making the object appear higher than it really is.
How are rainbows formed?
Light refracts into water droplets, reflects inside, then refracts again when leaving.
What is a lens?
A transparent material that refracts light to form an image.
What are the 2 main types of lenses?
Converging (convex) and diverging (concave).
What does a converging lens do?
Brings parallel rays together to a focal point.
What does a diverging lens do?
Causes parallel rays to spread apart.
What type of image does a converging lens usually produce?
A real image.
What type of image does a diverging lens produce?
A virtual image.
What happens to a ray parallel to the principal axis in a converging lens?
It refracts through the focal point.
What happens to a ray through the optical centre?
It continues straight without refracting.
What is the SALT for a diverging lens image?
Smaller, upright, virtual, and closer to the lens than the object.
What equation is used for lenses and mirrors?
1/f = 1/do + 1/di.
What is the magnification equation?
M = hi/ho = -di/do.
What does a positive focal length mean?
The lens is converging (convex).
What does a negative focal length mean?
The lens is diverging (concave).
What does a positive image distance mean?
The image is real and on the opposite side of the lens.
What does a negative image distance mean?
The image is virtual and on the same side as the object.
What did Galileo discover with his telescope?
Jupiter's moons, Moon craters, and phases of Venus.
What happened when Galileo increased magnification?
The field of view became smaller.
What problem affected Galileo's telescope?
Chromatic aberration.
What did Kepler improve in telescopes?
Greater magnification.
What drawback did Kepler's telescope have?
The image was inverted.
What is the objective lens?
The lens light enters through.
What is the eyepiece?
The lens you look through.
What is a refracting telescope?
A telescope that uses lenses.
What is a reflecting telescope?
A telescope that uses mirrors.
Why are most modern telescopes reflecting telescopes?
Mirrors are easier to make large than lenses.
What are binoculars?
Two refracting telescopes joined together.
Why do binoculars use prisms?
To improve magnification and make the image upright.
What is the purpose of a microscope?
To magnify tiny objects.
What does the objective lens do in a microscope?
Forms a real inverted image.
What does the eyepiece do?
Magnifies the image.
What is the cornea?
The curved front part of the eye that refracts light.
What is the retina?
The light-sensitive layer at the back of the eye.
What do rod cells detect?
Light.
What do cone cells detect?
Colour.
What controls how much light enters the eye?
The iris and pupil.
What carries messages to the brain?
The optic nerve.
How does the eye focus on objects?
The lens changes shape using ciliary muscles.
What part of the camera is like the retina?
Film or CCD.
What part of the camera is like the pupil?
Aperture.
How does a camera focus?
The lens moves in and out.
What is myopia?
Near-sightedness.
What causes myopia?
Eyeball too long.
What lens corrects myopia?
Diverging lens.
What is hyperopia?
Far-sightedness.
What causes hyperopia?
Eyeball too short.
What lens corrects hyperopia?
Converging lens.
What is presbyopia?
Stiffening of the eye lens with age.
How is presbyopia corrected?
Bifocals.
What causes astigmatism?
Unevenly shaped cornea.
What does astigmatism cause?
Blurry or distorted vision.
What does laser eye surgery do?
Changes the shape of the cornea.
What are risks of laser eye surgery?
Dry eyes, halos, double vision, sensitivity to light.
What do night-vision devices do?
Allow people to see in dim light.
What colour is the final image usually?
Green.
Why is the image green?
Human eyes are most sensitive to green light.