PHYSICS 3LC TEST QUESTIONS WITH VERIFIED SOLUTIONS GRADED A+
The photometer is a device that converts light to voltage which is read out by the digital
multimeter (DMM). This is due to the photoelectric effect. (Einstein won his Nobel Prize for his
explanation of the photoelectric effect.) In the photoelectric effect, light hits a piece of metal.
Quantum mechanics tells us that light can be thought of as tiny packets of energy called
photons. The photons are absorbed by electrons and increase the energy of the electrons.
Some of the electrons become so energetic that they escape from the metal. In other words
electrons are emitted from the metal, producing a current that is amplified by the photometer.
The current goes through a resistor in the photometer. Ohm's law (V=IR) tells us that current I
going through a resistor R is associated with a voltage drop V. The DMM measures the voltage
drop across the resistor. Saturation occurs when the metal emits the maximum flux of elect -
Answers What does a photometer do?
B. It converts light into electric current.
A. It emits light.
B. It converts light into electric current.
C. It measures the frequency of light.
D. It emits sound.
What are photons?
A. electrons
B. Tiny quantized packets of light.
C. protons
D. name of a rock group
E. neutrons - Answers B. Tiny Quantized Packets of light.
What happens in the photoelectric effect?
,A. Electrons hit a metal and electrons are emitted.
B. Light hits a metal and photons are emitted.
C. Electrons hit a metal and light is emitted.
D. Light hits a metal and protons are emitted.
E. Light hits a metal and electrons are emitted. - Answers E. Light hits a metal and electrons are
emitted.
In the photometer, light strikes a metal and electrons are emitted. The moving electrons
constitute a current that flows through a resistor . The digital multimeter (DMM) can be set to
read the voltage drop across the resistor . The DMM has a high input impedance (resistance)
that is in parallel with . Let's denote the input impedance . Note that .
Note that even with no input, e.g., the photometer turned off, the DMM set on 200 mV will
output a signal because of ambient electromagnetic waves, e.g., radio waves in the air. These
radio waves have an oscillating electric field that pushes electrons in the cable connected to the
DMM. These moving electrons constitute a small current. Recall Ohm's law: . For the DMM, we
can write . So if is large, even a tiny current can produce a finite voltage . This is why your DMM
will read a voltage even if the input cable is not connected to anything. The cable acts like an
anten - Answers Voltage
Which of the following DOES NOT describe projection imaging?
A. Images are formed by projecting a beam through the patient's body and casting shadows
onto an appropriate receptor
B. Spatial distortion is generally not a major problem
C. Produces images of selected planes or slices of tissue of the patient's body
D. A large volume of the patient's body can be viewed with one image
E. All of the above describe projection imaging. - Answers C. Produces Images of selected
planes or slices of tissues of the patient's body.
In projection imaging (radiography and fluoroscopy), images are formed by projecting a beam
through the patient's body and casting shadows onto an appropriate receptor that converts the
invisible beam image into a visible light image. The primary advantage of this type of image is
, that a large volume of the patient's body can be viewed with one image. A disadvantage is that
structures and objects are often superimposed so that the image of a superfluous object
interferes with the image of the structure under study. In projection imaging, spatial distortion is
generally not a major problem in most clinical applications.
Tomographic imaging techniques such as conventional tomography, computed tomography
(CT), sonography, single photon emission tomography (SPECT), positron emission tomography
(PET), and magnetic resonance imaging (MRI), produce images of selected planes or slices of
tissue of the patient's body. The general advantage of a tomographic image is the increased
visibility of objects within the imaged plane. One factor that contributes to this is the absence of
overlying objects. The major disadvantage is that only a small slice of a patient's body can be
visualized with one image. Therefore, most tomographic procedures usually require many
images to survey an entire organ system or body cavity. [1]
Which of the following DOES NOT describe tomographic imaging?
A. A large volume of the patient's body can be viewed with one image
B. Produces images of selected planes or slices of tissue of the patient's body
C. Includes PET and MRI scans
D. Increased visibility of objects within the imaged plane due to absence of overlying objects
E. All of the above describes tomographic imaging - Answers Large volumes of patients body
viewed with one image.
An ordinary dental X-ray uses which imaging technique(s)?
A. Sonography
B. Projection
C. Tomography
D. None of the above - Answers Projection
Depending on the application, a wide variety of particles and waves are used to probe the body.
The photometer is a device that converts light to voltage which is read out by the digital
multimeter (DMM). This is due to the photoelectric effect. (Einstein won his Nobel Prize for his
explanation of the photoelectric effect.) In the photoelectric effect, light hits a piece of metal.
Quantum mechanics tells us that light can be thought of as tiny packets of energy called
photons. The photons are absorbed by electrons and increase the energy of the electrons.
Some of the electrons become so energetic that they escape from the metal. In other words
electrons are emitted from the metal, producing a current that is amplified by the photometer.
The current goes through a resistor in the photometer. Ohm's law (V=IR) tells us that current I
going through a resistor R is associated with a voltage drop V. The DMM measures the voltage
drop across the resistor. Saturation occurs when the metal emits the maximum flux of elect -
Answers What does a photometer do?
B. It converts light into electric current.
A. It emits light.
B. It converts light into electric current.
C. It measures the frequency of light.
D. It emits sound.
What are photons?
A. electrons
B. Tiny quantized packets of light.
C. protons
D. name of a rock group
E. neutrons - Answers B. Tiny Quantized Packets of light.
What happens in the photoelectric effect?
,A. Electrons hit a metal and electrons are emitted.
B. Light hits a metal and photons are emitted.
C. Electrons hit a metal and light is emitted.
D. Light hits a metal and protons are emitted.
E. Light hits a metal and electrons are emitted. - Answers E. Light hits a metal and electrons are
emitted.
In the photometer, light strikes a metal and electrons are emitted. The moving electrons
constitute a current that flows through a resistor . The digital multimeter (DMM) can be set to
read the voltage drop across the resistor . The DMM has a high input impedance (resistance)
that is in parallel with . Let's denote the input impedance . Note that .
Note that even with no input, e.g., the photometer turned off, the DMM set on 200 mV will
output a signal because of ambient electromagnetic waves, e.g., radio waves in the air. These
radio waves have an oscillating electric field that pushes electrons in the cable connected to the
DMM. These moving electrons constitute a small current. Recall Ohm's law: . For the DMM, we
can write . So if is large, even a tiny current can produce a finite voltage . This is why your DMM
will read a voltage even if the input cable is not connected to anything. The cable acts like an
anten - Answers Voltage
Which of the following DOES NOT describe projection imaging?
A. Images are formed by projecting a beam through the patient's body and casting shadows
onto an appropriate receptor
B. Spatial distortion is generally not a major problem
C. Produces images of selected planes or slices of tissue of the patient's body
D. A large volume of the patient's body can be viewed with one image
E. All of the above describe projection imaging. - Answers C. Produces Images of selected
planes or slices of tissues of the patient's body.
In projection imaging (radiography and fluoroscopy), images are formed by projecting a beam
through the patient's body and casting shadows onto an appropriate receptor that converts the
invisible beam image into a visible light image. The primary advantage of this type of image is
, that a large volume of the patient's body can be viewed with one image. A disadvantage is that
structures and objects are often superimposed so that the image of a superfluous object
interferes with the image of the structure under study. In projection imaging, spatial distortion is
generally not a major problem in most clinical applications.
Tomographic imaging techniques such as conventional tomography, computed tomography
(CT), sonography, single photon emission tomography (SPECT), positron emission tomography
(PET), and magnetic resonance imaging (MRI), produce images of selected planes or slices of
tissue of the patient's body. The general advantage of a tomographic image is the increased
visibility of objects within the imaged plane. One factor that contributes to this is the absence of
overlying objects. The major disadvantage is that only a small slice of a patient's body can be
visualized with one image. Therefore, most tomographic procedures usually require many
images to survey an entire organ system or body cavity. [1]
Which of the following DOES NOT describe tomographic imaging?
A. A large volume of the patient's body can be viewed with one image
B. Produces images of selected planes or slices of tissue of the patient's body
C. Includes PET and MRI scans
D. Increased visibility of objects within the imaged plane due to absence of overlying objects
E. All of the above describes tomographic imaging - Answers Large volumes of patients body
viewed with one image.
An ordinary dental X-ray uses which imaging technique(s)?
A. Sonography
B. Projection
C. Tomography
D. None of the above - Answers Projection
Depending on the application, a wide variety of particles and waves are used to probe the body.
