Section 1
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3) Geologic evidence indicates that the magnetic field of the earth has
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Cards (59)
Section 1
(50 cards)
3) Geologic evidence indicates that the magnetic field of the earth has
often varied in both strength and direction.
10) If a magnetic field exerts a force on a moving charge, that force is directed
at right angles to the direction of motion
13) The fundamental wavelength for standing waves on a rope fixed at both ends is ________ the length of the rope.
two times
2) In the Rutherford model of the atom, nearly all the all of the volume occupied by the atom consists of
a vacuum
16) The secondary (output) coil of a neon-sign transformer provides 0.01 A of current at 7,500 V. The primary (input) voltage is 120 V. The current flowing through the primary coil of the transformer is
.625A
18) Does every magnet always have to have both a north and south pole?
yes
14) Usually one can touch the terminals of a low voltage battery with no dire consequences. Yet the intensive care wards in hospitals go to great effort and expense to ground all the electrical equipment in order to guard against the presence of even the lowest of voltage. Why are low voltages so hazardous in hospitals?
Most of the electrical resistance of the body is at the dry skin-air boundary. This high contact resistance is sufficient to prevent dangerous currents passing through the body. In a hospital, one may have needles or other probes penetrating this protective layer and so the electrical resistance is much lower. Thus fatal currents can result from relatively low voltages.
6) In order to have the current passing through the human body be more than 100 mA (which is fatal) when touching 120 V, the resistance would have to be
less than 1200 Ohm
2) What caused the Tacoma Narrows Bridge to collapse?
The frequency of the wind turbulence matched a resonant frequency of the bridge
9) What is the power of a light bulb that draws 2 A when it is plugged into a household electrical outlet?.
240W
4) A flashlight has two 1.5 D-cells placed end-to-end in series. The voltage across the combination is
3V
10) An air-condition uses 2000 Watts when plugged into a normal household circuit. The current flowing through the device is
16.7A
3) What force is responsible for holding the electrons in their orbits about the nucleus?
electric
5) Planck was able to obtain the correct curve for the spectrum of light emitted by a hot object by assuming that the
b. vibrational energies of the atomic resonators were quantized
17) Which of the following is NOT an electromagnetic waves?
ultrasound
8) While standing on a dock, you observe water waves passing beneath you. If you observe 20 waves passing directly below you in 2 minutes and judge the crests to be 1 m apart, what is the period of the waves?
6s
6) The velocity of a periodic wave is equal to its wavelength
divided by its period
11) Which of the following is a unit for measuring electric energy?
kilowatt * hour
14) A transformer can be used to change the
a voltage of ac electricity
2) The charge carriers for electrical current in a metallic conductor are the
electrons
1) The rate at which charge flows through a given section of a circuit each second is measured in
amperes
8) Magnetic resonance imaging records the
density of hydrogen nuclei
7) Normal household electricity is
120V ac
1) The spectral lines for elements are called atomic fingerprints because they
are unique to each element
1) If a bar magnet is broken into two pieces, each piece
has 2 magnetic poles
13) When the magnetic field through a loop of wire changes, a voltage is induced in the coil. If the coil had twice as many loops, then
twice the voltage is induced
15) A step-up transformer increases the
voltage
10) Sound waves are examples of
longitudinal waves
11) Sound waves with frequencies greater than 20,000 Hz are called
ultrasonic waves
3) The number of Ohms in a circuit is a measure of the
resistance to the flow of charge through the circuit.
7) If we compare the speed of a sound wave with a frequency of 220 Hz to that of a sound wave with a frequency of 440 Hz, the 220-Hz wave is moving _______as the 440-Hz wave.
at the same speed
5) The current through a 12 Ohm light bulb connected to a 6 V battery is
.5A
13) What causes the biological damage from electrical shock, the current or the voltage?
The physiological effects of electricity result from the current flow through the body over some time period. The size of the current depends on both the resistance of your body and the applied voltage, ie Ohm's law.
9) A proton with a speed v is moving perpendicular to a magnetic field B and thus experiences a force F. If the speed of the proton is doubled, the new force is
2F
1) A mass vibrates up and down on a vertical spring. If the period of the motion is two seconds, the frequency is
one-half cycle per second.
4) As the temperature of a incandescent radiating object increases, the frequency with the maximum brightness
increases
8) The charges carriers that are free to move in a metallic conducting wire are
the negatively charged electrons
5) Pigeons navigate primarily by
magnetic sensors in your head
6) In the space surrounding a wire carrying a steady electric current, there exists
a magnetic field that circles the wire.
4) The source of the Earth's magnetic field is presumably
the motion of charged particles in the outer layers of the molten core of the Earth
2) The North poles of two magnets will
repel each other
5) How far does a wave travel during one period?
wavelength
4) The distance from trough to trough on a periodic wave is called its
wavelength
12) A node of a standing wave is a
position of zero amplitude
12) In which of the following situations is an electric current not produced?
a coil of wire is wrapped around a stationary magnet
12) Which costs the most to operate? a 1500-W heater for 1 hour. a 200-W light bulb for 8 hour. 40-W refrigerator for 12 hours. a 15-W radio for 24 hours.
200W light bulb for 8 hour
3) A wave in which the individual particles of a medium vibrate back and forth perpendicular to the direction that the wave travels is called a
transverse wave
9) Middle C has a frequency of 262 Hz. If the velocity of sound in air is 340 m/s, what is the wavelength of the wave
1.3m
7) A strong magnet attracts a thumbtack with a 100 N force. The force that the tack exerts on the magnet is
equal to 100N
11) A magnetic field does not exert a force on
a stationary charge
Section 2
(9 cards)