Human Eye and Light Quiz

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What is the role of the iris in the human eye?

It protects the eye from foreign particles.

It gathers light and focuses it.

It controls the size of the pupil. (correct)

It forms the inverted image on the retina.

What happens to the ciliary muscles when viewing distant objects?

They stay neutral, with no change to the lens.

They contract and the lens becomes thick.

They weaken, causing the lens to lose elasticity.

They relax and the lens becomes thin. (correct)

What is the minimum distance at which objects can be seen without strain called?

Far point

Near point (correct)

Hyperopia

Accommodative distance

What characteristic of red light makes it suitable for use in stoplights?

It has a longer wavelength than blue light. (D) Signup and view all the answers

What condition is characterized by the inability to see distant objects clearly?

Myopia (D) Signup and view all the answers

What type of lens is used to correct hypermetropia?

Convex lens (C) Signup and view all the answers

What is presbyopia primarily caused by?

Gradual weakening of the ciliary muscles. (C) Signup and view all the answers

Which of the following is NOT a reason why we have two eyes?

To see the world in 2D. (C) Signup and view all the answers

What is the term for the splitting of light into its component colors?

Dispersion (B) Signup and view all the answers

Which color of light bends the least when passing through a prism?

Red (C) Signup and view all the answers

What phenomenon causes a rainbow to appear in the sky after a rain shower?

Dispersion of sunlight (A) Signup and view all the answers

Why do planets not twinkle like stars?

They are closer and appear as an extended source of light. (A) Signup and view all the answers

What causes the sky to appear blue on a clear day?

Molecules of air preferentially scatter blue light over red light. (D) Signup and view all the answers

What effect does rapid refraction have on the appearance of stars?

It makes stars appear flickering or twinkling. (B) Signup and view all the answers

Why does the sun appear to rise early and set late due to atmospheric refraction?

Refraction changes the apparent position of the sun. (A) Signup and view all the answers

What is responsible for the Tyndall effect observed when sunlight enters a dark room?

Scattering of light by fine and large particles. (D) Signup and view all the answers

What phenomenon describes the separation of white light into its component colors?

Dispersion. Signup and view all the answers

Name the scientist who first used a glass prism to observe the spectrum of sunlight.

Isaac Newton. Signup and view all the answers

Why do stars appear to twinkle while planets do not?

Stars twinkle due to atmospheric refraction, while planets appear steady because they are closer and seen as extended sources of light. Signup and view all the answers

What causes the phenomenon of a rainbow?

A rainbow is caused by the dispersion of sunlight through tiny water droplets in the atmosphere. Signup and view all the answers

Explain how atmospheric refraction affects the apparent position of stars.

Atmospheric refraction bends starlight towards the normal, making stars appear higher in the sky than their actual position. Signup and view all the answers

What effect causes the sky to appear blue during the day?

The sky appears blue because molecules of air scatter blue light more than red light due to their size being smaller than the wavelength of visible light. Signup and view all the answers

How does refraction in the atmosphere affect sunrise and sunset times?

Refraction makes the sun appear to rise 2 minutes early and set 2 minutes late compared to its geometric position. Signup and view all the answers

What is the Tyndall effect and give an example?

The Tyndall effect is the scattering of light by colloidal particles, seen when sunlight enters a dark room. Signup and view all the answers

What part of the eye regulates the amount of light entering and how does it function in different lighting conditions?

The iris regulates the amount of light by contracting in bright light and expanding in dim light. Signup and view all the answers

Explain how the eye accommodates for viewing distant and close objects.

For distant objects, the ciliary muscles relax, making the lens thin and increasing focal length; for close objects, the ciliary muscles contract, thickening the lens and decreasing focal length. Signup and view all the answers

What is a cataract, and how does it affect vision?

A cataract is the clouding of the crystalline lens, leading to blurry or impaired vision. Signup and view all the answers

Why do humans have two eyes, and what advantages does this provide?

Having two eyes enhances depth perception, provides a wider field of view, and improves the ability to detect faint objects. Signup and view all the answers

What is myopia, and what causes this condition?

Myopia, or near-sightedness, is the inability to see distant objects clearly, caused by excessive curvature of the lens or elongation of the eyeball. Signup and view all the answers

Describe hypermetropia and the typical corrective method.

Hypermetropia, or far-sightedness, occurs when nearby objects cannot be seen clearly, typically due to a focal length that is too long or a small eyeball. Signup and view all the answers

What is presbyopia, and how is it typically corrected?

Presbyopia is the gradual weakening of the ciliary muscles and diminished lens ability to adjust; it is typically corrected with bi-focal lenses. Signup and view all the answers

What is the role of the retina in the visual process?

The retina contains light-sensitive cells that generate electric signals when illuminated, sending them to the brain through optic nerves. Signup and view all the answers