1140 Questions & Blanks Flashcards
Why did scientists abandon Isaac Newton’s particle theory of light in 1850?
Jean Foucault discovered that light travels slower in water than in air.
Why do scientists have difficulty discovering truth?
They have a limited means of observing reality.
What are light waves?
The regular and rapid transverse vibrations of electric and magnetic fields that spread out evenly in all directions.
The frequency of sound is interpreted by the ear as ______
Pitch
The frequency of light is interpreted by the eye as:
Color
Six basic colors of the visible light spectrum
Red orange yellow green blue violet
The brightness of light is measured by its __________
Intensity or amplitude
The inverse square law for light intensity (brightness)
The intensity of light at a particular point is inversely proportional to the square of the distance of the object from the light source.
Light must be allows to expand in a spherical shell for the inverse square law to apply.
.
Four physical quantities that vary according to the inverse square law
The force of gravity Brightness of light Intensity of sound Magnetic fields Electrical fields
What did William Herschel conclude about the sun?
It radiates invisible waves
Infrared waves have a _______ than do visible light waves.
Longer wavelength
A blacktop road that is warmer than air
Radiates heat efficiently
Black dirt
Absorbs and radiates heat efficiently
A blacktop road that is cooler than the air
Absorbs heat efficiently
Aluminum foil
Absorbs and radiates heat poorly
Microwaves, radar, UHF, VHF, FM, AM
Increasing wavelength
Decreasing frequency
.
All electromagnetic waves can be _________
Reflected, refracted, or absorbed
Huygen’s principle of wave motion
Every point on a wave is itself a source of a new wave motion of the same frequency
What is diffraction?
a phenomenon in which waves spread out after they pass through a small opening and bend as they pass along the edge of an obstruction
When water waves strike a small standing obstruction, such as a post, they:
bend along the edge of the obstruction
How does diffraction affect microscopes and telescopes?
it limits their resolution
What does a diffraction grating do?
disperses light into the colors of the spectrum
Three advantages of diffraction gratings compared to glass prisms
produces greater dispersion
separate colors better
provide a uniform amount of separation from one color to the next
What is interference?
the interaction of two or more waves
Thomas Young’s experiment
light band resulted from constructive interference of light waves
dark bands resulted from destructive interference of light waves
Poor reception can occur when radio waves reach a receiver by two routes and ______
come together out of phase
Polarization occurs because light waves are ______
transverse
What happens when light waves enter certain crystal formations?
They are either absorbed or polarized along the plane of the crystal
To eliminate almost all light, two polarizing crystals must be aligned
perpendicularly to each other
How do two European television stations broadcast two signals of the same frequency without interference
one broadcasts horizontally polarized waves
the other broadcast vertically polarized waves
Lord Rayleigh
.
A body that is charged with static electricity always has
an unequal number of electrons and protons
The three laws of static electricity developed by Benjamin Franklin
Bodies charged with static electricity attract uncharged bodies. Like electric charges repel one another, unlike attract.
What happens when a negatively charged body is connected to a ground by a conductor?
it becomes neutral as excess electrons flow to the ground
Coulomb’s law
the force acting between two charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them
a coulomb is
the amount of charge that will produce a force of 1.0 Newton when placed 1.0 meter from a like charge
strongest force
nuclear
weakest force
gravitational
the potential difference between two points of an electrical field
the work-per-unit charge needed to move the charge from one point to another
What is an electrical field?
the region of force that surrounds a charged object.
(q1 x q2)/r^2
Coulomb’s law (answer in dynes when esu and cm)
What are two ways to increase capacitance?
increase charge or lower voltage
What procedure is used to make it possible to include large capacitors in electrical circuits?
The capacitor is made of flexible foil which is separated with waxed paper and then rolled into a cylinder
A _______ is one whose capacitance can be changed
variable capacitor
How is a variable capacitor created?
by holding one set of plates stationary while the other set pivots
If a charged rod is brought near an electroscope and the leaves collapse quickly, what happens?
The charges cannot be identified by this information
When a charged rod is brought near an electroscope, the leaves collapse quickly. When a rod of opposite charge is brought near, the leaves diverge farther. What is the charge of the electroscope?
The charge cannot be identified by this information.
If a charged rod is brought near an electroscope and the leaves diverge farther, what happens?
Either both are positive or both are negative
Explain how the Dewar flask reduces each type of heat loss to a minimum
A partial vacuum reduces heat transfer by conduction and convection, and the reflective silvered surface of the walls reduces heat transfer by radiation.
Coulomb’s law
the force of attraction between two charges is directly proportional to the product of the charges and inversely proportional to the square of the distances separating them.
What is the potential difference between two points of an electric field?
the work-per-unit charge needed to move the charge from one point to another
The three laws of static electricity as developed by Benji
Bodies charged with static electricity attract uncharged bodies.
Like electric charges repel each other.
Unlike electric charges attract each other.
If a charged rod is brought near an electroscope and the leaves diverge father, what happens?
Either both are positive or both are negative.
What is an electric field?
the region of force that surrounds a charged object
