Question

i need a quick answer pls

Answer 1

eyes, electrical, retinal

before, convex

after, concave

Answer 2

Answer:

retina, electrical, optic

before, concave

behind, convex

Stephen looks at a cat; the light that hits his retina produces a chemical reaction. This produces an electrical signal that travels up the optic nerve to the brain.

If you are short-sighted, the light focuses before the retina. To correct for this you need to wear glasses or contact lenses that contain concave lenses.

If you are long-sighted, the light focuses behind the retina. To correct for this you need to wear glasses or contact lenses that contain convex lenses.

Explanation

All the sensory systems follow a common basis. To sense or perceive something there should be a signal, then receptors to receive the signal, then nerves to transmit the signal to the brain. Then finally the brain process the signal and you sense or perceive it.

That is what happens in the visual system as well. For vision, the signal is the light that comes from an object. The light goes in through the pupil to go through the lens to finally be focused on the retina. Retina has receptors to receive the light signal. Receiving the signal, a chemical reaction occurs in the retina and an electrical impulse is generated. This impulse is taken to the brain by the nerve fibers which extend from the retina. These nerve fibers collectively form the optic nerve. i.e. Visual information is taken to the brain by the optic nerve.

Short-sighted means that you can see the near objects clearly, but the distant objects appear blurred. In this condition, the light focuses in front of the retina.

Long-sighted means that you can see the distant objects clearly, but the near objects appear blurred. In this condition, the light focuses behind the retina.

Both conditions can be corrected with glasses or contact lenses. The aim of the corrective lens is to bend the light rays in order to make them focus correctly on the retina.

In that way, short-sightedness should be corrected with concave lenses and long-sightedness with convex lenses.