Question 1

Why would it be impossible to obtain interference fringes in a double-slit experiment if the separation of the slits is less than the wavelength of the light used?

Accepted Answer

In no direction could a path difference as large as one wavelength be obtained, and this is needed if a bright fringe, in addition to the central fringe, is to be observed.

Question 2

Why does light seem to go straight through an open doorway whereas sound seems to spread out when it goes through the same doorway?

Accepted Answer

It has to do with the relative sizes of their wavelengths. The wavelength of light is << opening size so very small diffraction; sound wavelengths are >> opening so diffraction is significant.

Question 3

Discuss a similarity and a difference between the spectrum formed by a diffraction grating (a large number of slits) and that formed by just a double slit.

Accepted Answer

The maxima of both satisfy d sin(θ) = nλ, but the fringes formed by the grating are much sharper (narrow).

Question 4

How do interference and diffraction differ? How are they similar?

Accepted Answer

The answer of How do interference and diffraction differ? How...

Question 5

Discuss what you see viewing a distant street light through a thin curtain (at night).

Accepted Answer

The answer of Discuss what you see viewing a distant...

Question 6

If two light waves are coherent, which of the following is NOT necessary?
A) They must have the same velocity.
B) They must have the same wavelength.
C) They must have the same amplitude.
D) They must have the same frequency.
E) They must have a constant phase difference at every point in space.

Accepted Answer

Coherent light waves must have the same frequency and a constant phase difference, but they do not need to have the same amplitude.

Question 7

The experiments of what person first clearly demonstrated the wave nature of light?
A) Maxwell
B) Young
C) Newton
D) Einstein
E) Galileo

Accepted Answer

Thomas Young's double-slit experiment, conducted in the early 19th century, was crucial in demonstrating the wave nature of light. This experiment showed that when light passes through two close, parallel slits, it creates an interference pattern on a screen placed behind the slits, a phenomenon that can only be explained by the wave theory of light.

Question 8

Monochromatic light from a distant source is incident on two parallel narrow slits. After passing through the slits the light strikes a screen, as shown in Figure 24-1.

What will be the nature of the pattern of light observed on the screen?
A) A rainbow of colored lines will be seen spreading out on either side of point O.
B) The screen will be uniformly illuminated except for two dark bands, one in line with each slit.
C) There will be two bright bands of light, one in line with each slit.
D) There will be a series of alternating light and dark bands.
E) The screen will be most brightly illuminated at point O, with the intensity decreasing slowly and uniformly as you move outward from point O.

Accepted Answer

The answer of Monochromatic light from a distant source is...

Question 9

Constructive interference of two coherent waves will occur if the path difference is
A) 1/4 $\lambda$.
B) 6/4 $\lambda$.
C) 6/2 $\lambda$.
D) 3/4 $\lambda$.
E) 3/2 $\lambda$.

Accepted Answer

Constructive interference occurs when the path difference is an integer multiple of the wavelength, i.e., $ n\lambda $ where $ n $ is an integer. 6/2 $\lambda$ simplifies to 3$\lambda$, which is an integer multiple of $\lambda$.

Question 10

At the first maxima on either side of the central bright spot in a double-slit experiment, light from each opening arrives
A) in phase.
B) 45° out of phase.
C) 90° out of phase.
D) 180° out of phase.
E) -45° out of phase.

Accepted Answer

At the first maxima on either side of the central bright spot in a double-slit experiment, light from each opening arrives in phase. This constructive interference, where the waves are in phase, results in a bright fringe.

Question 11

Two beams of coherent light travel different paths arriving at point P. If the maximum constructive interference is to occur at point P, the two beams must
A) arrive 180° out of phase.
B) arrive 90° out of phase.
C) travel paths that differ by an odd number of half-wavelengths.
D) travel paths that differ by a whole number of wavelengths.

Accepted Answer

For maximum constructive interference to occur at point P, the two beams of coherent light must arrive in phase or have a phase difference that corresponds to a whole number of wavelengths. This ensures that the peaks of one wave align with the peaks of the other wave, and the troughs align as well, leading to constructive interference where the amplitude of the resultant wave is maximized.

Question 12

The path difference for destructive interference is m$\lambda$/2 where
A) m = 0, 1, 2, 3, ...
B) m = 2, 4, 6 , 8, ...
C) m = 0, 2, 4, 6, ...
D) m = 1, 3, 5, 7, ...
E) m = 1, 2, 3, 4, ...

Accepted Answer

For destructive interference, the path difference should be an odd multiple of $\lambda/2$, which corresponds to m = 1, 3, 5, 7, ...

Question 13

In a double-slit experiment, it is observed that the distance between adjacent maxima on a remote screen is 1 cm. What happens to the distance between adjacent maxima when the slit separation is cut in half?
A) It increases to 2 cm.
B) It decreases to 0.5 cm.
C) It increases to 4 cm.
D) It decreases to 0.25 cm.

Accepted Answer

The distance between adjacent maxima in a double-slit experiment is directly proportional to the slit separation. Halving the slit separation doubles the distance between maxima.

Question 14

At the second maxima on either side of the central bright spot in a double-slit experiment, light from
A) one opening travels two wavelengths of light farther than light from the other opening.
B) each opening travels the same distance.
C) one opening travels twice as far as light from the other opening.
D) one opening travels one wavelength of light farther than light from the other opening.

Accepted Answer

At the second maxima in a double-slit experiment, the path difference between the light from the two slits is two wavelengths. This condition is necessary for constructive interference to occur at that point, leading to a bright fringe.

Question 15

The separation between adjacent maxima in a double-slit interference pattern using monochromatic light is
A) greatest for blue light.
B) greatest for green light.
C) greatest for red light.
D) the same for all colors of light.

Accepted Answer

The separation between adjacent maxima in a double-slit interference pattern depends on the wavelength of the light used. Red light has a longer wavelength than blue or green light, leading to a greater separation between the maxima.

Question 16

The colors on an oil slick are caused by reflection and
A) refraction.
B) polarization.
C) interference.
D) diffraction.

Accepted Answer

The colors on an oil slick are caused by interference, which occurs when light waves reflected from the top and bottom surfaces of the thin oil layer combine, enhancing or canceling out certain wavelengths and producing the observed colors.

Question 17

The concentric fringes, formed when a curved lens is placed on an optical flat, are called
A) Galileo circles.
B) Faraday's circles.
C) Newton's rings.
D) Young's rings.
E) Maxwell circles.

Accepted Answer

Newton's rings are the concentric circular patterns observed when a curved lens is placed on an optical flat, resulting from the interference of light waves.

Question 18

After a rain, one sometimes sees brightly colored oil slicks on the road. These are due to
A) polarization effects.
B) selective absorption of different wavelengths by oil.
C) diffraction effects.
D) interference effects.
E) birefringence.

Accepted Answer

The brightly colored oil slicks seen on the road after rain are due to thin film interference effects, where light waves reflected from the top and bottom surfaces of the oil film interfere with each other, creating the colorful patterns observed.

Question 19

Liquid Crystal Displays (LCDs) depend upon which of the following for their operation?
A) coherence
B) thin film interference
C) diffraction
D) dichroism
E) polarization

Accepted Answer

LCDs operate based on the polarization of light, using liquid crystals to control the alignment of polarized light to display images.

Question 20

The polarization of sunlight is greatest at
A) sunrise.
B) sunset.
C) midday.
D) both sunrise and sunset.

Accepted Answer

The polarization of sunlight is greatest at both sunrise and sunset because the sunlight travels through a larger portion of the Earth's atmosphere, scattering more light and enhancing polarization at these times of day.

Quiz 24: Physical Optics: The Wave Nature of Light

Why would it be impossible to obtain interference fringes in a double-slit experiment if the separation of the slits is less than the wavelength of the light used?

Why does light seem to go straight through an open doorway whereas sound seems to spread out when it goes through the same doorway?

Discuss a similarity and a difference between the spectrum formed by a diffraction grating (a large number of slits) and that formed by just a double slit.

How do interference and diffraction differ? How are they similar?

Discuss what you see viewing a distant street light through a thin curtain (at night).

If two light waves are coherent, which of the following is NOT necessary?

The experiments of what person first clearly demonstrated the wave nature of light?

Monochromatic light from a distant source is incident on two parallel narrow slits. After passing through the slits the light strikes a screen, as shown in Figure 24-1. What will be the nature of the pattern of light observed on the screen?

Constructive interference of two coherent waves will occur if the path difference is

At the first maxima on either side of the central bright spot in a double-slit experiment, light from each opening arrives

Two beams of coherent light travel different paths arriving at point P. If the maximum constructive interference is to occur at point P, the two beams must

The path difference for destructive interference is m $\lambda$ /2 where

In a double-slit experiment, it is observed that the distance between adjacent maxima on a remote screen is 1 cm. What happens to the distance between adjacent maxima when the slit separation is cut in half?

At the second maxima on either side of the central bright spot in a double-slit experiment, light from

The separation between adjacent maxima in a double-slit interference pattern using monochromatic light is

The colors on an oil slick are caused by reflection and

The concentric fringes, formed when a curved lens is placed on an optical flat, are called

After a rain, one sometimes sees brightly colored oil slicks on the road. These are due to

Liquid Crystal Displays (LCDs) depend upon which of the following for their operation?

The polarization of sunlight is greatest at

Quiz 24: Physical Optics: The Wave Nature of Light

Why would it be impossible to obtain interference fringes in a double-slit experiment if the separation of the slits is less than the wavelength of the light used?

Why does light seem to go straight through an open doorway whereas sound seems to spread out when it goes through the same doorway?

Discuss a similarity and a difference between the spectrum formed by a diffraction grating (a large number of slits) and that formed by just a double slit.

How do interference and diffraction differ? How are they similar?

Discuss what you see viewing a distant street light through a thin curtain (at night).

If two light waves are coherent, which of the following is NOT necessary?

The experiments of what person first clearly demonstrated the wave nature of light?

Monochromatic light from a distant source is incident on two parallel narrow slits. After passing through the slits the light strikes a screen, as shown in Figure 24-1. What will be the nature of the pattern of light observed on the screen?

Constructive interference of two coherent waves will occur if the path difference is

At the first maxima on either side of the central bright spot in a double-slit experiment, light from each opening arrives

Two beams of coherent light travel different paths arriving at point P. If the maximum constructive interference is to occur at point P, the two beams must

The path difference for destructive interference is m λ\lambdaλ /2 where

In a double-slit experiment, it is observed that the distance between adjacent maxima on a remote screen is 1 cm. What happens to the distance between adjacent maxima when the slit separation is cut in half?

At the second maxima on either side of the central bright spot in a double-slit experiment, light from

The separation between adjacent maxima in a double-slit interference pattern using monochromatic light is

The colors on an oil slick are caused by reflection and

The concentric fringes, formed when a curved lens is placed on an optical flat, are called

After a rain, one sometimes sees brightly colored oil slicks on the road. These are due to

Liquid Crystal Displays (LCDs) depend upon which of the following for their operation?

The polarization of sunlight is greatest at

The path difference for destructive interference is m $\lambda$ /2 where