Physics Chapter 28 - Reflection and Refraction

When light reflects from a surface, there is a change in its

none of the above

3 multiple choice options

According to the law of reflection, the incident light ray, the reflected light ray, and the normal between them

lie in the same plane

Light is reflected when

incident light is returned into the medium from which it came

It is difficult to see the roadway when driving on a rainy night mainly because

the film of water on the roadway makes the road less diffuse

Your image in a plane mirror is

virtual

3 multiple choice options

The inversion of your image in a plane mirror is actually an inversion of

front-back

3 multiple choice options

Object and image for a plane mirror occur

Diffuse reflection occurs when the size of surface irregularities is

large compared to the wavelength of the light used

The shortest plane mirror in which you can see your entire image is

half your height

Light travels from one place to another along a path of least

fine

Refraction occurs when light passing from one medium to another

changes speed

When a light ray in air enters water at 15° from the normal, it

always bends toward the normal

A mirage is a result of atmospheric

refraction

Rainbows are not usually seen as complete circles because

the ground is usually in the way

Refraction causes the bottom of a swimming pool to appear

closer to the surface than it actually is

Light travels fastest in

a vacuum

The secondary rainbow is dimmer than the primary rainbow mainly because

of an extra reflection and refraction in the drops

When light passes through common windowpane, its angle of emergence is

the same as its angle of incidence

Reflection

returned into the medium from which it came

How does reflection work?

light hits a material and energizes it's electrons, the electrons release their excitement in the form of light

Fermant's Principle of Least Time

the idea that light takes the quickest path in going from one place to another

Angle of Incidence

made by the incoming ray and the perpendicular (surface)

Angle of Reflection

made by the reflected ray and the perpendicular (surface)

Normal

imaginary line perpendicular to the place of the reflecting surface (lies in the same place as the incident and reflected rays)

Law of Reflection

the angle of reflection equals the angle of incidence

Virtual Image

same size as an object, formed behind a mirror, and located at the position where the extended reflected rays converge is as far behind the mirror as the object is in front of the mirror

Plane Mirror

normal, regular mirror (the only axis reversed in an image is in the front-back axis)

Convex Mirror (that curves outward)

virtual image is smaller and close to the mirror than the object

Concave Mirror (that curves inward)

virtual image is larger and farther away from the object

Diffuse Reflections

when light strikes a rough or irregular surface and reflects in many directions (an undesirable circumstance is the ghost image that occurs on a TV set when TV signals bounce off buildings)

Different road surfaces determine amount of

diffuse reflection

Dry Road Surface

rough because of diffuse reflection, see road ahead of car at night

Wet Road Surface

smooth because of less diffuse, reflection, difficult to see

Light bends when going in obliquely (slantwise) from

one medium to another

Refraction

bending of light when it passes from one medium to another (caused by change in speed of light)

In general, when light enters a new materials

its direction will change

Total Internal Reflection

a phenomenon that occurs when a wave, such as a light wave, traveling through a medium encounters a boundary with another medium of lower refractive index at an angle greater than the critical angle

Lower refractive indices = _______________________________

closer to the speed of light

Critical Angle

the minimum angle of which a beam of light will be internally reflected (no longer refracts into air)

Critical angles vary for

different materials

Examples of Total Internal Reflection

glass prisms, optical fibers (biomedical devices, communications, etc.)

Converging Lens (convex)

bulges out (thicker in the center than the edges) and converges light

Diverging Lens (concave)

caves in (thinner in the center than the edges) and diverges lens

Principal Axis

line joining the centers of curvature of the two lens surfaces

Focal Point

point at which all the light rays come together

Focal Length

distance between the center of the lens and either focal point

Image formation is a consequence of

light traveling in straight lines (the first camera, the pinhole camera, illustrates this fact)

A converging lens can project an

image

Real images are always

upside down