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