OCR A LEVEL PHYSICS PAPER 2 WITH
QUESTIONS AND ANSWERS|| ALREADY
GRADED A+|| LATEST UPDATE 2026
What thickness of lead will stop a significant proportion of gamma rays? -
ANSWER-3-4cm
What provides the energy of the X-rays in an X-ray tube? - ANSWER-The
kinetic energy of the accelerated electrons.
What is an essential property for the target metal in an X-ray tube? - ANSWER-
High melting point.
State the range of wavelengths (in powers of 10) of ultraviolet - ANSWER-10⁻⁷
- 10⁻⁸
In an X-ray tube what happens to most of the kinetic energy lost by the
electrons when they hit the anode? - ANSWER-It is transferred to thermal
energy of the anode.
What measures can be taken to prevent an anode melting in an X-ray tube? -
ANSWER-It is cooled by oil or rotated
Why can't longitudinal waves be polarised? - ANSWER-Longitudinal waves
already only have a single driection of oscillation.
What feature of X-ray tubes protects the radiographer? - ANSWER-Lead lining.
,What is the effect of perpendicular polarising filters - ANSWER-No light is
transmitted
What determines the maximum frequency of X-rays produced in an X-ray tube?
- ANSWER-The maximum kinetic energy of a single electron.
What is the relationship between energy stored and p.d. on a capcitor? -
ANSWER-Energy stored is proportional to p.d. squared
What is the relationship between energy stored and charge on a capcitor? -
ANSWER-Energy stored is proportional to charge squared
Out of Q, V and I which variable(s) follow the relationship x = x0 e-(t/RC)
when discharging a capacitor? - ANSWER-Q, V and I
Out of Q, V and I which variable(s) follow the relationship x = x0 e-(t/RC)
when charging a capacitor? - ANSWER-I
What contrast medium is typically used to image the digestive system? -
ANSWER-Barium sulfate
How do you calculate time constant in a capcitor circuit? - ANSWER-RC
How are X-rays used for cancer therapy? - ANSWER-A linear accelerator
produces high energy X-rays that destroy cells.
How much charge remains after one time constant when discharging a
capacitor? - ANSWER-e-1 OR 0.37 OR 37%
,How much charge remains after n time constants when discharging a capacitor?
- ANSWER-e-n
What is represented by the gradient of charge-time graph when charging a
capacitor? - ANSWER-Charging current.
State a two uses of capacitors. - ANSWER-Energy storage e.g. for camera
flashes, spot welding..., timing circuits, voltage smoothing, audio filters.
What is an electric field? - ANSWER-A region of space where a charge will
experience an electrostatic force.
What is the definition of electric field strength? - ANSWER-The force per unit
charge on a positive test charge placed at that point
Why are high energy X-rays prefereable to gamma radiation for cancer therapy?
- ANSWER-An X-ray source can be turned off.
Which radionuclide is used for imaging with a gamma camera? - ANSWER-
Technitium-99m
What is an ultrasound A-scan? - ANSWER-A single transducer produce pulses
that travel along a single path through the patient?
What is the threshold frequency? - ANSWER-The minimum frequency of light
required to produce photoelectrons from a metal
How does an ultrasound A-scan calculate the distance to boundaries between
tissues? - ANSWER-2 x Distance = v x t, where v is the speed of the ultrasound
and t is the time interval between the emitted and reflected pulse.
, What is the relationship between work function and threshold frequency? -
ANSWER-∅ = hf₀
What is an ultrasound B scan? - ANSWER-The signal from an array of
transducers is processed by computer to build up a 2D image.
Why can't light sources below the threshold frequency produce photoelectrons?
- ANSWER-The photon energy is less than the work function
How do photons and electrons interact? - ANSWER-A single photon can be
absorbed/emitted by a single electron which gains/loses the energy of the
photon.
What is the effect on an electron of absorbing a photon? - ANSWER-The
electron gains the energy of the photon
What effect does increasing the frequency of a monochromatic light source
have on photoelectrons produced? - ANSWER-Photoelectrons will have a
greater maximum kinetic energy
What determines the brightness of the dots on a B scan display? - ANSWER-
The amplitude of the reflected ultrasound from that point.
What determines the acoustic impedence of a substance? - ANSWER-The
density and the speed of sound in the substance.
What are the units of acoustic impedance? - ANSWER-kgm⁻²s⁻¹
What is the intensity reflection coefficient for ultrasound? - ANSWER-The ratio
(reflected intensity of ultrasound ÷ incident intensity of ultrasound)
QUESTIONS AND ANSWERS|| ALREADY
GRADED A+|| LATEST UPDATE 2026
What thickness of lead will stop a significant proportion of gamma rays? -
ANSWER-3-4cm
What provides the energy of the X-rays in an X-ray tube? - ANSWER-The
kinetic energy of the accelerated electrons.
What is an essential property for the target metal in an X-ray tube? - ANSWER-
High melting point.
State the range of wavelengths (in powers of 10) of ultraviolet - ANSWER-10⁻⁷
- 10⁻⁸
In an X-ray tube what happens to most of the kinetic energy lost by the
electrons when they hit the anode? - ANSWER-It is transferred to thermal
energy of the anode.
What measures can be taken to prevent an anode melting in an X-ray tube? -
ANSWER-It is cooled by oil or rotated
Why can't longitudinal waves be polarised? - ANSWER-Longitudinal waves
already only have a single driection of oscillation.
What feature of X-ray tubes protects the radiographer? - ANSWER-Lead lining.
,What is the effect of perpendicular polarising filters - ANSWER-No light is
transmitted
What determines the maximum frequency of X-rays produced in an X-ray tube?
- ANSWER-The maximum kinetic energy of a single electron.
What is the relationship between energy stored and p.d. on a capcitor? -
ANSWER-Energy stored is proportional to p.d. squared
What is the relationship between energy stored and charge on a capcitor? -
ANSWER-Energy stored is proportional to charge squared
Out of Q, V and I which variable(s) follow the relationship x = x0 e-(t/RC)
when discharging a capacitor? - ANSWER-Q, V and I
Out of Q, V and I which variable(s) follow the relationship x = x0 e-(t/RC)
when charging a capacitor? - ANSWER-I
What contrast medium is typically used to image the digestive system? -
ANSWER-Barium sulfate
How do you calculate time constant in a capcitor circuit? - ANSWER-RC
How are X-rays used for cancer therapy? - ANSWER-A linear accelerator
produces high energy X-rays that destroy cells.
How much charge remains after one time constant when discharging a
capacitor? - ANSWER-e-1 OR 0.37 OR 37%
,How much charge remains after n time constants when discharging a capacitor?
- ANSWER-e-n
What is represented by the gradient of charge-time graph when charging a
capacitor? - ANSWER-Charging current.
State a two uses of capacitors. - ANSWER-Energy storage e.g. for camera
flashes, spot welding..., timing circuits, voltage smoothing, audio filters.
What is an electric field? - ANSWER-A region of space where a charge will
experience an electrostatic force.
What is the definition of electric field strength? - ANSWER-The force per unit
charge on a positive test charge placed at that point
Why are high energy X-rays prefereable to gamma radiation for cancer therapy?
- ANSWER-An X-ray source can be turned off.
Which radionuclide is used for imaging with a gamma camera? - ANSWER-
Technitium-99m
What is an ultrasound A-scan? - ANSWER-A single transducer produce pulses
that travel along a single path through the patient?
What is the threshold frequency? - ANSWER-The minimum frequency of light
required to produce photoelectrons from a metal
How does an ultrasound A-scan calculate the distance to boundaries between
tissues? - ANSWER-2 x Distance = v x t, where v is the speed of the ultrasound
and t is the time interval between the emitted and reflected pulse.
, What is the relationship between work function and threshold frequency? -
ANSWER-∅ = hf₀
What is an ultrasound B scan? - ANSWER-The signal from an array of
transducers is processed by computer to build up a 2D image.
Why can't light sources below the threshold frequency produce photoelectrons?
- ANSWER-The photon energy is less than the work function
How do photons and electrons interact? - ANSWER-A single photon can be
absorbed/emitted by a single electron which gains/loses the energy of the
photon.
What is the effect on an electron of absorbing a photon? - ANSWER-The
electron gains the energy of the photon
What effect does increasing the frequency of a monochromatic light source
have on photoelectrons produced? - ANSWER-Photoelectrons will have a
greater maximum kinetic energy
What determines the brightness of the dots on a B scan display? - ANSWER-
The amplitude of the reflected ultrasound from that point.
What determines the acoustic impedence of a substance? - ANSWER-The
density and the speed of sound in the substance.
What are the units of acoustic impedance? - ANSWER-kgm⁻²s⁻¹
What is the intensity reflection coefficient for ultrasound? - ANSWER-The ratio
(reflected intensity of ultrasound ÷ incident intensity of ultrasound)
