Refraction and Lenses

What is refraction?

The bending of light as it is transmitted through transparent material.

What happens when a light wave passes from air into water at an angle?

Its speed decreases and causes the light ray to refract toward the normal.

What happens to a light wave if its speed increases during refraction?

It would bend away from the normal.

Why does refraction occur?

Due to wave changing speed because light travels fastest in air, slower in liquids, and slowest in solids.

What is the index of refraction?

The ratio of the speed of light in a vacuum to a given material, denoted by n.

What formula represents the index of refraction?

n = c/v.

What is Snell’s Law?

A formula used to describe the relationship between the angles of incidence and refraction when referring to light or other waves passing through a boundary between two different media.

What is the formula for Snell’s Law?

n1sinx1 = n2sinx2.

Why do objects appear at a different place from where they really are?

Due to refraction.

What can cause a noticeable change in light speed?

Air temperature.

What is a mirage?

A distorted image caused by a refraction of light in Earth’s atmosphere.

In which temperature does light travel fastest?

Hot air.

How do you know if the light is bending towards or away from the normal?

If it is traveling from a lower n to a denser region, it will bend towards the normal; otherwise, it bends away.

What is an internal reflection?

A consequence of the refraction of light.

When does total internal reflection occur?

When the angle of incidence is larger than the critical angle and light is going from a slower moving medium to a faster moving medium.

What are optical fibers?

Light pipes; transparent fibers that transport light from one place to another.

What is dispersion?

The separation of white light into colors arranged according to their frequency.

What is a lens?

A piece of glass or plastic that refracts light.

How does a lens form an image?

By bending parallel rays of light that pass through it.

What do all lenses rely on?

On light having a slower speed in the lens as it goes from gas (air) to solid (lens).

What is a converging lens?

A convex lens, thicker in the middle and thinner at the edges, causing rays of light to appear to originate from a single point.

What is a diverging lens?

A concave lens, thinner in the middle and thicker at the edges, causing rays of light to appear to originate from a single point.

What kind of contact lenses do far-sighted people use?

Convex lenses.

What kind of contact lenses do near-sighted people use?

Concave lenses.