Chapter 6 & 7 Flashcards
An automobile headlight draws a current of 6 amperes, operating on 12 volts . The resistance of the headlight in ohms is
2
Suppose current is flowing in a wire from right to left. Which way do the electrons in the wire move?
left to right.
A heater is rated at 1200 watts for a 120 volt source. The current in amperes drawn by the heater is
10
If a compact fluorescent lightbulb (CFL) breaks, the Environmental Protection Agency (EPA) recommends that hazardous material (HazMet) cleanup procedures be followed. This is because it contains which hazardous material
mercury
What is the speed of sound in the air in meters/second inside a furnace where the temperature is 500 degrees Celsius (773 Kelvin)?
558.8
You pull on a rope with a certain force, and a wave travels in the rope with a certain velocity. If you exert four times as much force, the velocity of a wave in the rope is now _____ the original velocity.
2 times
Why do we use fuses and circuit breakers?
to prevent fires.
A light bulb used in a slide projector draws a current of 6 amperes when operating on 120 volts. The power consumed by the light bulb in watts is
720
Water ripples are produced by making a cork oscillate up and down at a frequency of 5 Hz. The peaks of the ripples are 0.03 meters apart. What is the speed in meters/second of the water ripples?
0.15
The term “ultrasound” is applied to waves which have a much greater _____ than sound waves.
frequency
What is the usual symbol used to represent an amount of charge?
q
You shout at a cliff, and hear your echo in 2 seconds. If the speed of sound in the air is 340 m/s, the distance of the cliff from you in meters is
340
The energy in Joules used by a 100 watt light bulb in 1 hour is
360000
Which of the following is not an example of real time ultrasound?
B-Mode Scanner
the SI unit of electric charge
Coulomb
an atom with fewer electrons than protons
positive ion
type of current supplied by a battery
DC current
employed in appliances like toasters and hair dryers
ohmic heating
the SI unit of current
Ampere (Amp)
consists of charges flowing back and forth
AC current
rate of flow of electric charge
electric current
used to change AC voltages
transformer
the energy per unit charge supplied by a battery
voltage
like charges do this
repel
a quanity that measures the opposition to the flow of charges
resistance
In the laboratory, the instructor gives you an unknown resistor to identify. Using a multimeter, you measure a current of 1.5 ma through the resistor, and a voltage of 3.3 V across it. What is the resistance in ohms?
2,200
A battery operating a large flashlight produces a current of 2 amperes in a light bulb that has a resistance of 4 ohms. The voltage of the battery (in volts) is
8
An example of a longitudinal wave is a
(A) sound wave in air. (B) wave on a rope. (C) water wave. (D) ultrasound wave in a human body. (E) none of the above.
A and D
Two charged bodies separated by a distance d exert an electrical force on each other. The charge on one of the bodies is doubled. The electrical forces on each body now
double.
Real time phased array ultrasound uses the principle of _____________ to sweep an ultrasound beam through a sector of the body.
constructive interference.
A negative ion is formed when
a neutral atom gains an electron.
line used to show the path of a wave
ray
occurs when the amplitudes of two waves add together because they arrive at the same place in phase
constructive interference
any material through which a wave travels
wave medium
sound waves used to form images of internal organs
ultrasound
the maximum displacement of points on a wave
amplitude
the number of cycles of a wave passing a point per unit time
frequency
an echo occurs because of ___________ of a sound wave
reflection
the distance between two successive ‘like’ points on a wave
wavelength
an ultrasound wave through the body is an example of this type of wave
longitudinal wave
the distance between peaks of a wave divided by the time for the wave to travel this distance
wave velocity
If three identical bulbs are connected in parallel across a 12V battery, the voltage across each bulb will be
12V.
You have two identical ropes stretched with the same force between two different sets of posts. The second rope is twice as long as the first rope. The velocity of a wave in the second rope is _____ the velocity of a wave in the first rope.
the same as
The wavelength of a wave multiplied by the frequency of the wave is the wave’s
velocity
What is meant by “like charges?”
charges with “like sign,” ie, both positive or both negative.
A test tone used on a radio has a frequency of 1,000 Hz. What is the wavelength in meters of this sound in air at normal room temperature? (The speed of sound is 344 meters per second at room temperature.)
0.344
Two charged bodies separated by a distance d exert an electrical force on each other. The distance d is doubled. The electrical force on each body now
decreases by 1/4.
Two sound waves traveling through the air have different frequencies. Consequently, they must also have different
wavelengths
Electrons are
negatively charged.
A light bulb used in a slide projector draws a current of 6 amperes when operating on 120 volts. The resistance of the light bulb in ohms is
20
If I short out a D cell and draw a current of 7 A for 5 s, how many coulombs of charge move through the circuit?
35
Sound and Ultrasound are produced when something vibrates, causing nearby molecules to vibrate as a longitudinal wave.
True or False?
True
