OCR A A-Level Physics Paper 2 Exam Study Guide
Questions and Answers Rated 100% Correct
Describe how ultrasound scanning is used to obtain diagnostic information about internal
structures of a body. - Answer -Pulses of ultrasound (sent into the body)
-Wave / ultrasound / pulse / signal is reflected (at boundary of tissue)
-Time of delay used to determine depth / thickness
-The fraction of reflected signal is used to identify the
tissue
Describe the piezoelectric effect - Answer The application of a p.d. across a material / crystal causes
an expansion / contraction / vibration
Describe the differences between an A-scan and a
B-scan - Answer -A-scan in one direction only / range or distance or depth
finding
-B-scan uses a number of sensors or a sensor in different
positions / angles (to build up a 2D/3D image)
Alpha-particle scattering experiment is... - Answer evidence of a small, charged nucleus
Simple nuclear model of the atom... - Answer the atom is mostly space with a very small, very dense
positively charged nucleus and negatively charged electrons located in the atomic space.
The relative size of the nucleus of an atom is... - Answer 10^-15 (metres)
The relative size of an alpha particle is... - Answer 10^-10 (metres)
The strong nuclear force... - Answer acts between all nucleons. It is a short range force, effective over a
few femtometres. Attractive above (approx.) 3fm and repulsive below (approx.) 0.5fm.
,Radius of a nucleus - Answer R = r0 A^(1/3), in which r0 is a constant and A is the nucleon number
Rutherford Gold Foil Experiment Procedure - Answer Pointed a beam of alpha particles at a thin foil of
metal and measured the scattering pattern by using a fluorescent screen.
Rutherford Gold Foil Experiment Findings - Answer 1. They spotted alpha particles bouncing off the
metal foil in all directions, some right back at the source.
2. Only very few were deflected by large amounts (>90 degrees)
Rutherford Gold Foil Experiment Conclusions - Answer 1. The atom's positive charge was concentrated
in a much tinier volume than Thomson imagined.
2. Tiny spheres of intense positive charge were separated by vast gulfs of empty space.
X-ray - Answer Electromagnetic radiation with wavelength ranging from 0.1 to 10 nanometres
x-ray tube - Answer A piece of equipment that produces x ray photons by firing electrons from a beta
cathode across a large PD in an evacuated tube-x ray photons are produced when the electrons are
decelerated by hitting the target metal of the anode.
Thermionic emission - Answer The release of electrons from the surface of a heated material
Attenuation - Answer The decrease of intensity of electromagnetic radiation as it passes through matter
and/or space
Attenuation coefficient - Answer A measure of the absorption of x-ray photons by a substance. Also
called absorption coefficient
CAT scan - Answer Computer Axial Tomography; x-ray images taken in a ring around the body to
produce a composite 2d image
, Medical tracer - Answer A compound labelled with a radioisotope that can be traced inside the body
with a gamma camera
Collimator - Answer Part of a gamma camera, a honeycomb of long thin tubes made from lead that
absorbs any photons arriving at an angle to the axis of the tubes so that a clear picture is obtained
Scintillator - Answer Part of a gamma camera, that produces thousands of visible photons when struck
by a single gamma photon
Photomultiplier tube - Answer A piece of equipment that converts a photon of visible light into an
electrical pulse
PET scan - Answer Positron emission tomography scan; forms an image from the 2 gamma rays
produced during the annihilation of a positron and an electron
Ultrasound - Answer Sound that is higher frequency than the typical limit of human hearing (20kHz)
Ultrasound transducer - Answer A device used both to generate and to receive ultrasound which
changes electrical energy into sound and sound into electrical energy
Piezoelectric effect - Answer When electric charge accumulates in a solid material due to an applied
mechanical stress, producing a potential difference
Acoustic impedance - Answer The product of the density and the speed of ultrasound in a substance
Intensity reflection coefficient - Answer The ratio of reflected intensity to incident intensity at a
boundary
Coupling gel - Answer A gel with acoustic impedance similar to that of skin smeared onto the transducer
and the patient's skin before an ultrasounds scan in order to fill air gaps and ensure that almost all the
ultrasound enters the patient's body
Questions and Answers Rated 100% Correct
Describe how ultrasound scanning is used to obtain diagnostic information about internal
structures of a body. - Answer -Pulses of ultrasound (sent into the body)
-Wave / ultrasound / pulse / signal is reflected (at boundary of tissue)
-Time of delay used to determine depth / thickness
-The fraction of reflected signal is used to identify the
tissue
Describe the piezoelectric effect - Answer The application of a p.d. across a material / crystal causes
an expansion / contraction / vibration
Describe the differences between an A-scan and a
B-scan - Answer -A-scan in one direction only / range or distance or depth
finding
-B-scan uses a number of sensors or a sensor in different
positions / angles (to build up a 2D/3D image)
Alpha-particle scattering experiment is... - Answer evidence of a small, charged nucleus
Simple nuclear model of the atom... - Answer the atom is mostly space with a very small, very dense
positively charged nucleus and negatively charged electrons located in the atomic space.
The relative size of the nucleus of an atom is... - Answer 10^-15 (metres)
The relative size of an alpha particle is... - Answer 10^-10 (metres)
The strong nuclear force... - Answer acts between all nucleons. It is a short range force, effective over a
few femtometres. Attractive above (approx.) 3fm and repulsive below (approx.) 0.5fm.
,Radius of a nucleus - Answer R = r0 A^(1/3), in which r0 is a constant and A is the nucleon number
Rutherford Gold Foil Experiment Procedure - Answer Pointed a beam of alpha particles at a thin foil of
metal and measured the scattering pattern by using a fluorescent screen.
Rutherford Gold Foil Experiment Findings - Answer 1. They spotted alpha particles bouncing off the
metal foil in all directions, some right back at the source.
2. Only very few were deflected by large amounts (>90 degrees)
Rutherford Gold Foil Experiment Conclusions - Answer 1. The atom's positive charge was concentrated
in a much tinier volume than Thomson imagined.
2. Tiny spheres of intense positive charge were separated by vast gulfs of empty space.
X-ray - Answer Electromagnetic radiation with wavelength ranging from 0.1 to 10 nanometres
x-ray tube - Answer A piece of equipment that produces x ray photons by firing electrons from a beta
cathode across a large PD in an evacuated tube-x ray photons are produced when the electrons are
decelerated by hitting the target metal of the anode.
Thermionic emission - Answer The release of electrons from the surface of a heated material
Attenuation - Answer The decrease of intensity of electromagnetic radiation as it passes through matter
and/or space
Attenuation coefficient - Answer A measure of the absorption of x-ray photons by a substance. Also
called absorption coefficient
CAT scan - Answer Computer Axial Tomography; x-ray images taken in a ring around the body to
produce a composite 2d image
, Medical tracer - Answer A compound labelled with a radioisotope that can be traced inside the body
with a gamma camera
Collimator - Answer Part of a gamma camera, a honeycomb of long thin tubes made from lead that
absorbs any photons arriving at an angle to the axis of the tubes so that a clear picture is obtained
Scintillator - Answer Part of a gamma camera, that produces thousands of visible photons when struck
by a single gamma photon
Photomultiplier tube - Answer A piece of equipment that converts a photon of visible light into an
electrical pulse
PET scan - Answer Positron emission tomography scan; forms an image from the 2 gamma rays
produced during the annihilation of a positron and an electron
Ultrasound - Answer Sound that is higher frequency than the typical limit of human hearing (20kHz)
Ultrasound transducer - Answer A device used both to generate and to receive ultrasound which
changes electrical energy into sound and sound into electrical energy
Piezoelectric effect - Answer When electric charge accumulates in a solid material due to an applied
mechanical stress, producing a potential difference
Acoustic impedance - Answer The product of the density and the speed of ultrasound in a substance
Intensity reflection coefficient - Answer The ratio of reflected intensity to incident intensity at a
boundary
Coupling gel - Answer A gel with acoustic impedance similar to that of skin smeared onto the transducer
and the patient's skin before an ultrasounds scan in order to fill air gaps and ensure that almost all the
ultrasound enters the patient's body
