Chapter 28 and 33 quiz

Her eye at point P looks into the mirror. Which of the numbered cards can she see reflected in the mirror? (Figure 1)

2

No glass is perfectly transparent. Mainly because of reflections, about 92 % of light passes through an average sheet of clear windowpane. The 8 % loss is not noticed through a single sheet, but through several sheets, the loss is apparent. How much light is transmitted by a double-paned window (one with two sheets of glass)?

84%

If an object is placed a great distance away from and in front of a converging lens such as the one shown in the video, where will its image be formed?

It will be very near the focal point on the opposite side of the lens.

In the demonstration portion of the video, you were asked to think about the image of a candle formed by a concave mirror. Suppose that the lower half of the mirror were covered with black tape. How would that affect the image?

The entire image would remain but would become dimmer.

Light normally travels in straight lines, but it "bends" in an optical fiber. Explain.

Total internal reflection keeps the light trapped inside the optical fiber.

What did Henri Becquerel discover about uranium?

Uranium emitted radiation that would expose film and could be deflected by electric and magnetic fields

Why is lead found in all deposits of uranium ore?

Uranium undergoes radioactive decay, transmuting into lead.

Which travels more slowly in glass, red light or violet light? Why?

Violet light travels slower because it is closer in frequency to the ultraviolet resonance of the atoms in the glass.

Distinguish between a converging lens and a diverging lens.

When two parallel rays of light pass through a converging lens, the rays bend towards each other. When they pass through a diverging lens, the rays move apart from each other.

The discovery of radioactivity closely followed the discovery of _________.

X-Rays

Is the human body radioactive? Explain.

Yes. The potassium in our bodies has a radioactive isotope that is the main internal source of radiation for a human body.

An element that undergoes radioactive decay becomes _________.

an entirely different element

(Figure 1) shows a candle placed on the principal axis of a spherical concave mirror with the focal point F. One ray of light is shown leaving the center of the candle flame and reflecting off the mirror. This can be treated as _____________.

an incident ray passing through the focal point

Which of these ejects into the atmosphere the greatest amount of dangerous radiation?

coal-fired power plants

X-rays are most similar to which of the following - alpha, beta, or gamma rays?

gamma rays

What change in atomic number occurs when a nucleus emits an alpha particle? A beta particle? A gamma ray

-2, +1, 0

What is the half-life of Ra-226?

1620 years

At what angle inside glass is light totally internally reflected? At what angle inside a diamond is light totally internally reflected?

43°, 24.5°

A butterfly at eye level is 16 cm in front of a plane mirror. You are behind the butterfly, 50 cm from the mirror.What is the distance between your eye and the image of the butterfly in the mirror?

66 cm

When light strikes glass perpendicularly, about 4.8 % is reflected at each surface Find what percent of light is transmitted through a pane of window glass.

91%

Distinguish between a rad and a rem.

A rad measures energy absorbed, whereas a rem measures biological damage done.

What is a radioactive tracer?

A radioactive isotope of an element that by itself or in a molecule is used to trace biochemical pathways in plants and organisms

What kind of lens can be used to produce a real image? A virtual image?

A real image can only be made with a converging lens. A virtual image can be made with either a converging or diverging lens.

What kind of trail is left when an energetic particle shoots through matter?

A trail of free electrons and positive ions

Does a viewer see a single color or a spectrum of colors coming from a single faraway drop?

A viewer sees a single color from a single faraway drop

Which of the following is a true statement about virtual images?

A virtual image is formed at the position from which the rays appear to have originated.

What is the change in the atomic mass number for each of the reactions in the preceding two questions?

Alpha emission -4, beta emission 0

What is astigmatism, and how can it be corrected?

Astigmatism is caused when the cornea has a different radius of curvature in one direction compared to another. It is cured by adding a lens with a different radius of curvature in two different directions.

Identical rays of light in air are refracted upon entering three transparent materials: A, water, where the speed of light is 0.75c; B, ethyl alcohol (speed 0.7c); C, crown glass(speed 0.6c). (Figure 1) Rank the materials according to how much the light ray bends toward the normal, from most bending to least bending.

C,B,A

Rank these three types of radiation by their ability to penetrate a page of a book, from greatest penetration to least. A. Alpha particle. B. Beta particle. C. Gamma ray.

C,B,A

When, and by whom, did the first successful intentional transmutation of an element occur?

Ernest Rutherford, 1919

Which has the higher frequency: X-rays or gamma rays?

Gamma rays

Why aren't gamma rays deflected in a magnetic field?

Gamma rays are electromagnetic radiation and so have no charge. Electric and magnetic fields deflect charges.

Which type of detector senses radiation by the ionization of gas in a tube?

Geiger counter

Does a single raindrop illuminated by sunlight deflect light of a single color or does it disperse a spectrum of colors? Does it do this by reflection, refraction, or both?

It disperses a spectrum of colors, by both reflection and refraction.

How does refraction change the apparent depth of a swimming pool?

It makes the pool look shallower - only ¾ as deep.

What did Wilhelm Roentgen discover about a cathode-ray beam striking a glass surface?

It produced X-rays.

Which contains the higher percentage of neutrons: large nuclei or small nuclei?

Large nuclei (more than 50%)

Why is vision sharpest when the pupils of the eye are very small?

Light passes only through the center of the lens, where aberrations are minimal

What is Fermat's principle of least time?

Light takes the quickest path in going from one place to another.

Do humans receive more radiation from artificial or natural sources of radiation? What fraction comes from this source?

Natural, about 80%

What is the role of neutrons in the atomic nucleus?

Neutrons contribute strong nuclear force attraction without adding in electric force repulsion, so they help hold the nucleus together

What occurs when a nitrogen nucleus captures an extra neutron?

None of the above.

What two elements did Pierre and Marie Curie discover?

Polonium and radium

Name the two different nucleons.

Proton and neutron

Is a mirage the result of reflection or refraction? Why does it happen?

Refraction. Light curves through warm, low-density air near the ground, where it travels faster.

Which of these radiation detectors converts flashes of light into electric signals?

Scintillation counter

Which type of detector senses flashes of light produced by charged particles or gamma rays?

Scintillation counter

Cite the law of reflection.

The angle of incidence equals the angle of reflection.

Why doesn't the repulsive electrical force of protons in the atomic nucleus cause the protons to fly apart?

The attractive strong nuclear force holds the nucleus together

What is transmutation? Give one example.

The change of one chemical element into another, such as uranium to lead

Relative to the distance of an object in front of a plane mirror, how far behind the mirror is the image?

The image is the same distance behind the plane mirror as the object is in front of it.

What is the relationship between index of refraction and the speed of light in a material?

The index of refraction is inversely proportional to the speed of light in a material

What is meant by critical angle?

The minimum angle of incidence inside a medium where light is totally reflected

How does the rate of decay of a long-half-life material normally compare to the rate of decay of a short-half-life material?

The rate of decay is lower for a long-half-life material

Why is a secondary rainbow dimmer than a primary bow? How are the colors arranged in the secondary bow?

There is a second reflection with a loss of light. The colors are in the opposite order of the primary bow, with red on the inside instead of the outside.

Which is more prevalent in the food we eat: carbon-12 or carbon-14?

There is about one carbon-14 atom for every 100 billion carbon-12 atoms.

Does the law of reflection hold for curved mirrors? Explain.

Yes. It is as if the curved mirror is made of many small plane mirrors at slightly different orientations to each other.

What fraction of the light shining straight at a piece of clear glass is reflected from the first surface?

about 4%

The blackness of the type on a page is due to _________.

absorption

What kind of rays are X-rays?

electromagnetic

Which type of radiation - alpha, beta, or gamma - predominates within an enclosed elevator descending into a uranium mine?

gamma

Which of these is electromagnetic radiation?

gamma radiation

A feature of a pinhole camera is that the image _________.

is inverted

What is the long-range fate of all the uranium that exists in the world?

it will turn into lead

All the uranium in today's deposits in the future will become _________.

lead

Total internal reflection occurs when the speed of light in a material is _________.

less than the speed outside the material

Carbon-14 in the atmosphere is transformed from _________.

nitrogen

Which of these comprises the least radiation in the everyday environment?

nuclear power plants

If a certain isotope has a radioactive half-life of 10 years, how much of the isotope will remain at the end of 20 years?

one quarter

The strong force is one of the four fundamental forces in nature, and exists _________.

only between particles in the nucleus

What type or types of image can be displayed on a screen (for example, on a blank sheet of white paper)?

real

Dispersion of light from drops making up a rainbow have undergone refraction and internal _________.

reflection

A mirage is the result of atmospheric _________.

refraction

Waves don't overlap in the image of a pinhole camera. Does this feature contribute to sharpness or to a blurry image?

sharpness

Which of the following changes when light is refracted?

speed

How does the angle at which a ray of light strikes a pane of window glass compare with the angle at which it passes out the other side?

the angles are the same

She looks at her face in the handheld mirror.Rank the amount of her face she sees in the three locations, from greatest to least. Or is it the same in all positions?

they are all the same

In the multiple images of physics teacher Karen Jo Matsler in (Figure 1), how many mirrors are involved?

three mirrors

Light travels a path from one location to another in the least _________.

time

The diameter of the Sun makes an angle of 0.53∘ from Earth.How many minutes does it take the Sun to move 1 solar diameter in an overhead sky? (Remember that it takes 24 hours, or 1440 minutes, for the Sun to move through 360∘).How does your answer compare with the time it takes the Sun to disappear, once its lower edge meets the horizon at sunset? Does refraction affect your answer?

2.1 minutes It is the a little shorter than time it takes the Sun to disappear. yes

When thorium (atomic number 90) decays by emitting an alpha particle, what is the atomic number of the resulting nucleus?When thorium decays by emitting a beta particle, what is the atomic number of the resulting nucleus?

88 91

Distinguish between a virtual image and a real image. Mention in each case whether the image made by a single lens is right-side up or inverted.

A virtual image, unlike a real image, cannot be displayed on a screen. A virtual image is upright, whereas a real image is inverted.

Wheels from a toy cart are rolled from a concrete sidewalk onto the following surfaces: A, a paved driveway; B, a grass lawn; C, close-cropped grass on a golf-course putting green. Due to slowing, each set of wheels bends at the boundary and is deflected from its initial straight-line course.Rank the surfaces according to the amount each set of wheels bends at the boundary, from greatest amount of bending to least.

B,C,A

How does incident light that falls on an object affect the motion of electrons in the atoms of the object?

Incident light makes the electrons oscillate. The electrons then emit light or absorb the light and convert it to heat.

In which medium does light travel faster - thin air or dense air? How does this affect the length of daylight hours?

It travels faster in thin air, which makes sunlight curve and extends the length of the day.

What is the focal length of a lens? What is the focal point?

The distance between the center of the lens and either focal point is the focal length. The focal point is the point where a beam of parallel light, parallel to the principal axis, converges or appears to converge.

Why is a larger nucleus generally less stable than a smaller nucleus?

The electric force of repulsion between protons is a long-range force, while the attractive strong nuclear force is short-range. Repulsion wins for larger nuclei.

When the wheel of a cart rolls from a smooth sidewalk onto a plot of grass, the interaction of the wheel with the blades of grass slows the wheel. What slows light when it passes from air into glass or water?

The light oscillates electrons in the atoms of the glass or water. The electrons absorb some of the energy and reemit it after a delay at each atom.

Which of the following positions of an object will create a real image if the lens is a converging lens as shown in the video?

The object is very far from the lens.

What do the electrons affected by illumination do when they are made to vibrate with greater energy?

They reemit more light or collide with neighbors, thereby converting light energy to more internal energy.

Are eyeglasses made with "high index of refraction" materials thinner or thicker? Why?

Thinner. Light bends more entering high index of refraction materials.

When is the angle at which a ray of light strikes glass not the same as the angle it exits?

When the light strikes the glass in one medium (such as air) and exits the glass in another medium (such as water)

Can a surface be considered polished for some waves and not for others? Cite an example.

Yes. The mesh of a radio dish is polished for long wavelength radio waves and yet rough for short wavelength light waves.

A secondary rainbow in the sky is the result of a _________.

a double reflection in drops

Specular reflection is common in the light reflected from _________.

a mirror

What is the angle between a light ray and its wavefront?

a right angle

A magnifying glass widens the angle through which _________.

an object is viewed

If a nearsighted person wants thinner eyeglasses, is a higher or a lower index of refraction for the lenses recommended?

higher

When a flashlight submerged in water shines up into the air above, does the speed of light increase or decrease when the light passes from water into the air?

increases