physical science exam 2
a transformer is to be used to step down voltage from an alternating current source from 250 V to 110 V. if the primary has a current of 15 A. then the current in the secondary is?
34.1 A 250/110 = x 15
the current in a 60-w, 12-v light bulb is
5A 60 = I x 12
what light is
a mixture of all frequencies and colors of light
what unit is used for current
amperes
radio waves travel through space at what speed?
at the speed of light. 2.998 x 10 to the power of 8 m/s
to an astronaut in orbit around the earth, the sky appears
black
on earth, the sky appears blue because
blue light is scattered better than other wavelength
the wavelength of the wave shown in the figure above is
c
Atoms and molecules are normally
c. electrically neutral
what type of lens is this
concave lens the lens is caved in
the nucleus of an atom
contains most of the atoms mass
a changing magnetic field will induce a
current
the amplitude of the wave shown in the figure above is
d
V=IR is a statement of
d. Ohm's Law
compared to visible light, x-rays have
higher frequency and shorter wavelength.
a rainbow always appears
in the part of the sky opposite of the sun
for some Christmas lights, one broken bulb will cause the entire strand to go out. this is because
is a series circuit
the greater the decibel level of a sound wave, the
louder it is
a changing electric field gives rise to
magnetic field
the earth's geographic north pole is a
magnetic south pole
The current with which a transformer is used
must be ac
which of the following is used for the unit of resistance
ohm
speed of a photon
or the speed of light
in a longitudinal wave, the individual particles of the medium move
parallel to the direction of the wave
in a transverse wave, the individual particles of the medium move
perpendicular to the direction of the wave
two waves can combine with each other in a way that either amplifies or cancels out the original light waves. what is this behavior called
polarization
The volt is the unit of electric
potential difference
which of the following has the least energy, lowest frequency, and longest wavelength
radio waves
photons of which of the following colors of light posses the least energy
red
which color has the longest wavelength
red
a pencil in a glass appears bent. this is an example of
refraction
when light travels from air to glass, it ______, or bends
refracts
a circuit that has a single path for current to take is referred to as a
series circuit
gamma rays are dangerous because they are high energy, high frequency, with a ____
short
radio waves are
short
you look down at a pond that is 2 m deep. which of the following statements is true?
the pond will look less deep than 2 m
the higher the frequency of a wave
the shorter its wavelength
it takes .3 seconds for the sound of a whistle being blown to travel the length of a football field on a cold winter day with a temperature of 0 degrees Celsius. if the whistle is instead blown on a warm summer's day, how will the sound's travel time compare?
the sound travel time will be less on a warm day compared to a cold day because when it is warmer outside there is more particles in the air form sound to travel through.
light waves are transverse waves
true
protons and electrons have equal masses
true
the speed of light in space is 3 x 10 to the power of 8 m/s
true
the speed of sound in air is temperature-dependent.
true
when waves travel from one place to another, the carry energy.
true
An atom consists of a
uniform distribution of negative charge in which electrons are embedded.
purely longitudinal wave
water wave
the current in a 20-ohms electric heater operated at 240 V is
12 A V = IR 240 = 20 x I
ocean waves with a period of 10 s are found to have a wavelength of 120 m. their speed is
12m/s 120/12=12
a space heater draws a current of 15-A when connected to a 220- v power source. its resistance is?
14.7 ohms V=IR 220/15 + 15R R=14.67
a proton in an atom circulates around its nucleus
false
a typical atom is negatively charged
false
charge moving through a wire produces a magnetic field around the wire
false
depending on the time of day, the rainbow's color will be in different colors.
false
opposite charges repel, like charges attract
false
resistance is measured in watts
false
sound waves are transverse waves
false
bill and Fred are out on a spacewalk when bills suit communication system goes down. he shouts to Fred about it, but Fred cannot hear him. why cant Fred hear him.
sound cannot travel through the empty, airless space between them.
which of the following waves CANNOT travel through a vacuum
sound waves
in a transformer, if the primary coil contains more loops than the secondary coil, then it is a
step-up transformer
a fire truck races toward you. as it is moving toward you, the sound is high pitched, while the sound from the vehicle moving away lowers in pitch. this is an example of
the Doppler effect
When light of a particular frequency hits certain metallic surfaces, electrons are emitted by the surface. This is a description of
the Photoelectric effect
electric current is
the electrical equivalent of gravitational potential energy