Reflection, Refraction, Dispersion, and Diffraction

Visible light waves are:

A

longitudinal, and require a medium through which to propagate.

B

longitudinal, and do not require a medium through which to propagate.

C

transverse, and require a medium through which to propagate.

D

transverse, and do not require a medium through which to propagate.

D

Select all of the following wave types that could propagate through a vacuum, such as outer space.

A

Radio waves

B

Sound waves

C

Microwaves

D

Infrared radiation

A C D

Frequency can be measured in units of:

A

Hz.

B

seconds.

C

seconds / cycle.

D

1 / Hz.

A

Through which of these media will a radio wave travel more slowly than it would travel through outer space? (Select all that apply)

A

Medium X (n = 1.10)

B

Medium Z (n = 3.00)

C

Medium H (n = 2.13)

D

Medium M (n = 1.81)

ALL

Outer space is the classic example of a vacuum, meaning that it has an index of refraction of 1.00. (Remember, radio waves are electromagnetic and thus travel at the speed of light.) The higher the index of refraction, the slower light travels through a medium.

The index of refraction of diamond is 2.42. With what speed would an electromagnetic wave travel through a large diamond engagement ring?

A

1.24 × 108 m/s

B

3.00 × 108 m/s

C

5.42 × 108 m/s

D

7.26 × 108 m/s

A

reflection

The bouncing back of a wave when it hits a surface through which it cannot pass, the angle of incidence and angle of reflection are identical but opposite; both are determined from the normal (perpendicular line)

refraction

The bending of a wave and change in velocity as it passes at an angle from one medium to another

speed of sound

340 m/s

speed of light in a vacuum

3.00 x 10^8 m/s

refractive index

n = c/v

refractive index of air and water

air n = 1

water n = 1.33

Snell's Law

n1sinθ1 = n2sinθ2

Critical angle

the angle of incidence that produces an angle of refraction of 90 degrees

total internal reflection

the complete reflection that takes place within a substance when the angle of incidence of light striking the surface boundary is less than the critical angle

light is traveling from a material with a high n to a material with a lower n

angle of incidence is relatively large

Snell's law, which describes the bending of light passing from one medium to the next, is defined by which of the following equations?

A

n1sinθ2 = n2sinθ1

B

n1sinθ1 = n2sinθ2

C

θ1sinn1 = θ2sinn2

D

θ1sinn2 = θ2sinn1

B

A beam of sunlight hitting the surface of a pool of water will potentially (select all that apply):

A

reflect off the surface at an angle symmetrical to the angle at which it hits the surface.

B

reflect off the surface at an angle less than the angle at which it hits the surface.

C

refract through the medium at an angle symmetrical to the angle at which it hits the surface.

D

refract through the medium at an angle less than the angle at which it hits the surface.

A D

True or false: The critical angle is defined as an angle of incidence of 90 degrees.

True

False

False

The critical angle is the angle of incidence at which the angle of refraction is equal to 90 degrees, i.e. the angle of incidence at which total internal reflection occurs (remember that light cannot refract at an angle greater than 90 degrees).

Dispersion

light waves passing through a glass prism are broken up and dispersed into their component wavelengths

violet refracts more than red light

Diffraction

The bending of a wave as it moves around an obstacle or passes through a narrow opening

Single slit defraction

Asin(theta) = mλ

"a" is the width of the slit, and "m" an integer 1, 2, 3

Double Slit Defraction

Dsin(theta) = mλ

D - distance between apertures

X ray diffraction

an analytical method in which X-rays change direction on contact with matter, resulting in changes in radiation intensity, that is used to determine the three-dimensional arrangement of atoms.

process used by Rosalind Franklin to make images of DNA that helped reveal the structure of DNA

thin film interference

a phenomenon in which a spectrum of colors is produced due to the constructive and destructive interference of light waves reflected in a thin film

When a wave encounters a barrier with a small opening, some waves will hit the barrier and be reflected back, while other waves will pass through the opening and expand outward. This phenomenon is known as:

A

dispersion.

B

diffraction.

C

refraction.

D

reflection.

B

Select all of the following that are differences between single and double-slit diffractions.

A

Double-slit diffractions produce more even distributions of maxima and minima.

B

Single-slit diffractions produce only a single intensity peak, while double-slit diffractions produce two intensity peaks.

C

Double-slit diffractions can diffract all waves, while single-slit diffractions can only diffract light.

D

Single-slit diffractions cause light to engage in constructive, but not destructive interference with itself.

A only

Both single and double-slit diffractions produce a central intensity peak with many smaller intensity peaks off to the sides. The noticeable difference between the patterns is that, in single-slit diffraction, a greater proportion of the intensity ends up in the central peak than in double-slit diffraction.

True or false: In addition to their applications in physics research, diffraction techniques were instrumental in determining the structure of DNA.

True

False

True

A ray of violet light leaves a vacuum and directly enters a benzene solution. At the interface between the vacuum and benzene, this ray:

A

bent toward the normal, because light travels faster in benzene than in a vacuum.

B

bent away from the normal, because light travels faster in benzene than in a vacuum.

C

bent toward the normal, because light travels more slowly in benzene than in a vacuum.

D

bent away from the normal, because light travels more slowly in benzene than in a vacuum.

C

A light ray enters a diamond (n = 2.42) from the air (n = 1.00). What is the critical angle of incidence at which total internal reflection will occur?

A

24.2°

B

65.8°

C

90°

D

This situation could never result in total internal reflection.

D

This situation could never result in total internal reflection.

This situation involves movement from a low-index material into a high-index one. Total internal reflection can only occur when attempting to transition the other way (from a high-index material into a low-index one).

For incident angles greater than 48,8° total internal reflection will occur.

Select all of the following characteristics that decrease significantly when a light ray travels from air (n ≈ 1.00) into glass (n ≈ 1.5).

A

Frequency

B

Wavelength

C

Velocity

D

Period

B C

Material A has a slightly higher index of refraction than Material B, which has a slightly higher index than Material C. If identical light rays were to enter each of these materials from a vacuum, which would bend the most significantly toward the normal?

A

The ray entering Material A

B

The ray entering Material B

C

The ray entering Material C

D

None of the rays; all would bend away from the normal.

A

A glass prism can separate (disperse) light into its component pieces. Which of the following properties of an electromagnetic wave can change when entering or exiting a medium? Select all that apply.

A

Wavelength

B

Velocity

C

Color

D

Frequency

A B