Physical Science Ch. 6 & 7
The musical note A has a frequency of 440 Hz and its wavelength in seawater is 3.5 m. The speed of sound in seawater is
1540 m/s.
A charge of +Q attracts a charge of -Q 1 cm away with a force of F. Another charge of +Q is placed next to the first one. The force on the charge of -Q is now
2F
A boat at anchor is rocked by waves whose crests are 50 m apart and whose speed is 10 m/s. These waves reach the boat once every
5 s.
The voltage needed to produce a current of 8 A in a resistance of 12 ohms is
96 V.
Interference in the waves is the ____ together of two or more waves of the same kind that pass by the same point and at the same time.
adding
Electromagnetic waves are
combined electrical and magnetic disturbacnes
An electric charge involves the gain or loss of ______ from an object; these particles do not leave the object until there is a discharge.
electrons
The ____ carried by an electromagnetic field is constantly being exchanged between its fluctuating electric and magnetic fields.
energy
Frequency
is the number of cycles per second
Protons and electrons have different masses. When they are the same distance apart, the electric force between two electrons
is the same as the force between two protons.
Relative to its object, a real image formed by a lens is always
larger
You are looking at the bottom of a lake 1.2 m deep from a boat. To you the lake seems to be
less than 1.2 m deep.
Shadows are not completely dark because _____
light waves are able to diffract around the object causing the shadow
Relative to the focal length of a wide-angle camera lens, the focal length of a telephoto lens is
longer
The more energy a sound wave carries, the _______ it will sound.
louder
The greater the decibel (dB) level of a sound wave, the
louder it is.
The amplitude of a sound wave determines its
loudness
The current with which a transformer is used
must be ac.
An eye with the defect of farsightedness has trouble bringing into focus objects that are, _____ and in nearsightedness, the eye has trouble bringing into focus _____ objects.
near, distant
A ground fault interpreter works by breaking the circuit faster than a fuse or circuit breaker can by ______.
noting a current difference between the load-carrying wire and the system ground wires
The ratio of 1 volt to 1 amp defines the unit of resistance called an ______.
ohm
Polarized light can be made by passing light through a material that _______.
only allows light aligned in a certain direction to pass
Doubling the rate of energy flow producing a particular sound will make the loudness of the sound produced _____.
only slightly louder
A current-carrying loop in a magnetic field always tends to turn until the plane of the loop is
parallel to the field.
The number of seconds per cycle is called the wave's _____, and the number of cycles per second is the wave's _____
period, frequency
In an electromagnetic wave, the electric field is
perpendicular to both the magnetic field and the wave direction.
In a transverse wave, the individual particles of the medium move
perpendicular to the direction of travel.
Refracted light is light that has been bent from a straight path. Light that is turned sharply without being bent is called _____ light.
reflected
A lens is a piece of glass or other transparent material that can produce an image by ____ light that comes from an object.
refracting
The change in direction of a light ray when it passes from one substance into another (from water into air) is called ______.
refraction
A positive electric charge
repels other positive charges.
Dispersion is the term used to describe the
splitting of white light into its component colors in refraction.
A magnetic field does not interact with a
stationary electric charge.
Wavelength Period Speed
the distance between two identical point on adjacent waves the amount of time for a wave to repeat itself the rate of motion of the wave
Larger lenses are needed for higher magnification because the larger the lens ____
the less significance diffraction is
Wave crest Wave trough Amplitude
the maximum disturbance from the undisturbed position the maximum disturbance in the opposite direction from the rest position the maximum displacement from the rest position
When a rubber rod is stroked with a piece of fur,
the rod becomes negatively charged and the fur becomes positively charged.
The location where beams of light appear to come from behind a diverging lens is called a(n) ____ focal point because the light rays do not actually pass through that spot.
virtual
An example of a wave that is partly longitudinal and partly transverse is a
water wave.
Relative to the electric force between two protons, the gravitational force between them is
weaker.
Refraction of light ray occurs
when a light ray changes direction passing through the boundary between two materials
The watt, the unit of power, is equal to the
(volt)(ampere).
A 80-dB sound carries more energy than a 40-dB sound by a factor of
10,000
The standard home in the United States is wired with 120V. If a coffee maker draws a current of 10A, the resistance in it is _________ coulomb.
12 R=V/I, therefore, 120V/10A=12 coulombs.
Ocean waves with a period is 10 s are found to have a wavelength of 120 m. Their speed is
12 m/s.
Ocean waves whose period is 8 s are observed to have a wavelength of 100 m. Their speed is
12.5 m/s.
The speed of light in a transparent plastic whose index of refraction is 1.5 is
2 × 108 m/s.
Two 240-watt light bulbs are connected in parallel across a 120-V power line. The current in each bulb is
2.0 A.
The primary coil of a transformer has 200 turns and its secondary coil has 50 turns, and the current in the secondary coil is 40 A. When a 12-V alternating current is applied to the primary coil of the transformer, the secondary voltage will be
3 V.
Radio amateurs are permitted to communicate on the "10-meter band". What frequency of radio waves corresponds to a wavelength of 10 meters? The speed of radio waves is 3 × 108 m/s.
3.0 × 107 Hz
A medal in a plastic cube whose index of refraction is 1.5 appears to be 20 mm below the upper surface of the cube. The depth of the medal is actually
30mm.
The primary coil of a transformer has 200 turns and its secondary coil has 40 turns. If the current in the secondary coil is 25 A, the current in the primary coil is
5 A.
The ratio of the speed of light in a vacuum to the speed of light in a material is called the
Index of refraction Mathematically n=c/v
Electric neutrality of an object occurs where there is _____.
a balance of negative and positive charges
Longitudinal waves cause vibrations to occur in ______.
a direction parallel to their own environment
Relative to the radio signals sent out by a spacecraft headed away from the earth, the signals that are received on the earth have
a lower frequency.
A changing electric field gives rise to
a magnetic field
White light is best described as _____
a mixture of many colors
If two waves meet, the sum of the two separate _____ determines the resulting wave's amplitude.
amplitudes
When we look into a mirror, we appear to be behind the surface of the mirror. This is because light ______.
appears to travel in a straight line whereas it is really being reflected off the surface of the mirror
Newton's law of gravity and Coulumb's law are both fundamental laws and resemble each other in equation form. However, a major difference is gravitational forces _______.
are always attractive, but electric forces can be attractive or repulsive
The sky appears to be blue because
blue wavelengths are the most easily scattered in the atmosphere
Longitudinal waves create pulses of jammed-together molecules called ______ and alternatively pulses of thinned-out molecules called ______.
compressions; rarerarefractions
specialize in color vision specialized for low light conditions but cannot detect color
cones rods
Energy is carried in an electromagnetic wave by ______.
constantly being exchanged between the fluctuating electric and magnetic fields
A lens that brings parallel beams of light into single focal point is called a ____ lens.
converging
The image shows the path of light in the eye of a person who is farsighted. The light can be made to focus on the retina by using a ____ to ____ the light rays before they enter the eye.
converging lens; coverage
The blank scale ____ is used to describe the power of sound.
decibel
The ability of all waves to bend around the edge of an obstacle in their path is called _____
diffraction
The bending of waves around the edge of an obstacle in their path is an example of
diffraction.
A(n) _____ charge is produced whenever there is an imbalance between positive and negative charges.
electric
The excess number of electrons multiplied by the charge of one electron gives the ______.
electric charge
The conventional unit of battery capacity is the ampere-hour, which is actually a unit of
electric charge.
The particle easiest to remove from an atom is an
electron.
The greater the amplitude of a wave, the greater its
energy.
An eyeball that is too short will cause light from nearby objects to come into focus behind the retina (out of focus on the retina). This condition is known as ____
farsightedness
A converging lens of focal length f produces a real image of a real object when the object is
farther than f from the lens.
An electric field is subjected to a magnetic field that is parallel to it. As a result of the interaction, the electric field will ______.
feel nothing
The distance from a converging lens to the point where all the light rays come together is called the ____ of the lens.
focal length
The two magnetic poles of a magnet are where the _______.
forces of attraction seem concentrated
Overtones occur at those _____ that produce standing waves in a string attached at both ends.
frequencies
The property of light waves that leads to the phenomenon of color is
frequency
When a sound wave goes from air into water, the quantity that remains unchanged is its
frequency
A sound wave whose frequency is 50 Hz
has a relatively long wavelength.
Superconductors
have no electrical resistance.
Amplitude
is the largest displacement from the equilibrium position
Period
is the number of seconds per cycle
Maglev trains are trains that use _______.
magnetic forces to "levitate" the trains to eliminate friction
No matter how many times you cut a magnet in half, each piece will itself have a north and South Pole. This line of evidence supports the idea that ______.
magnetism is property of individual atoms
If a bar of iron is magnetized, the overall magnetic field is the result of ________.
many or all the iron atoms aligning
At different places on the earth's surface, the earth's magnetic field
may be different in both magnitude and direction.
Wavelengths are measured in
meters
Traveling at the speed of light in space, the electric and magnetic fields of an electromagnetic wave are _____ to each other and _____ to the direction of travel of the wave.
perpendicular, perpendicular
Which one of the following effects does not occur in all types of wave?
polarization
A simple way to find the properties of the image formed by a lens is to do
ray tracing
The image the lens of the eye forms on the retina is
real and inverted.
Light of which of the following colors has the longest wavelength?
red
An atom consists of a
small positive nucleus surrounded at a distance by electrons.
An example of a purely longitudinal wave is a
sound wave.
Of the following kinds of waves, the ones that cannot travel through a vacuum are
sound waves.
An electric current contains some device in which work is done (a lamp, for example) and therefore must contain a device that gives the _______.
source of energy to move the charges
Sound waves of frequency 300 Hz have a speed relative to sound waves in the same medium of frequency 600 Hz that is
the same
Two charges of +Q are 1 cm apart. If one of the charges is replaced by a charge of -Q, the magnitude of the force between them is
the same.
Dispersion of light means
the separation of light into different colors sorted by wavelengths
Cornea Retina Optic Nerve Ciliary muscle
the transparent outer membrane the light-sensitive part that converts when is seen into nerve impulses carries impulses to the brain changes the shape and focal length of the lens to focus on objects at different distances
Sound waves whose frequency is 300 Hz have a wavelength relative to sound waves in the same medium whose frequency is 900 Hz that is
three times as great.
Direct electric current cannot be used to operate
transformers.
Mechanical Waves
traveling vibrations in a medium
Sound waves of frequency 300 Hz have a wavelength relative to sound waves in the same medium of frequency 600 Hz that is
twice as great
Sonar (both medial and nautical) uses sounds with frequencies in the _____ range.
ultrasound
Sound waves with frequencies greater than 20,000 Hz are known as _____, whereas though with frequencies of less than 20Hz are known as _____.
ultrasound, infrasound
Curved mirrors, such are those used to look around blind corners, produce a ____ image.
virtual
A frequency that is not an overtone of the fundamental frequency F is
F/2
