A current is present in the circuit below.
The resistor is made from a length of wire.
Which row gives the correct charge carriers in the resistor and in the electrolyte?
| Charge carriers in the resistor | Charge carriers in the electrolyte | |
| A | Electrons | Electrons |
| B | Electrons | Ions |
| C | Electrons and protons | Ions and electrons |
| D | Electrons and ions | Ions and protons |
Your answer
[1]
The half-life of fluorine-18 isotope is T. After time t = 4 T the number of fluorine-18 nuclei in a source is N.
How many fluorine-18 nuclei have decayed in the time interval from t = 0 to t = 4 T ?
A 3 N
B 4 N
C 15 N
D 16 N
Your answer
[1]
A potential divider circuit is shown below.
The battery has electromotive force (e.m.f.) 9.0 V and negligible internal resistance. At room temperature the potential difference (p.d.) across the thermistor is 4.5 V. The temperature of the thermistor is increased and its resistance decreases by 20% from its previous value.
What is the p.d. across the thermistor now?
A 3.6 V
B 4.0 V
C 5.0 V
D 5.4 V
Your answer
[1]
A particle is moving at right angles to a uniform magnetic field of flux density B. The particle has mass m, charge q and moves in a circular arc of radius r in the region of the magnetic field.
What quantities are required to determine the momentum of this particle?
A B, q and r
B B, q and m
C B, q, r and m
D q, r and m
Your answer
[1]
A student is investigating the refraction of light by a rectangular glass block. The glass block is surrounded by air. The diagram below shows the path of the light as it enters the block, when it is refracted within the block and when it exits the block.
Which statement is correct?
A The angles 
and 
are the same because the glass block is surrounded by air.
B The product of sin 
and the refractive index of glass is a constant.
C The refractive index of glass is less than the refractive index of air.
D The speed of light is the same in both air and glass.
Your answer
[1]
A beam of sound of intensity I0 is reflected off the surface of water. The amplitude of the reflected sound is 
the amplitude of the incident sound. What is the intensity of the reflected sound in terms of I0?
D I0
Your answer
[1]
A wire in a circuit obeys Ohm’s law.
Which statement about the wire is linked to this law?
A The current in the wire is directly proportional to the potential difference across it.
B The current in the wire is inversely proportional to its resistance.
C The resistance of the wire is directly proportional to its length.
D The resistance of the wire is inversely proportional to its cross-sectional area.
Your answer
[1]
An electron has both mass and charge. The electron has a gravitational field and an electric field around it.
Which statement is not correct?
A Both field patterns look the same.
B Both field patterns show parallel field lines around the electron.
C Both field strengths obey an inverse square law with distance from the electron.
D The direction of both fields is the same at any point around the electron.
Your answer
[1]
A graph of displacement s against distance x for a progressive wave at time t = 0 is shown
Determine:
the phase difference 
in radians between the points on the wave at x = 1.5 cm and x = 2.5 cm
[1]
the displacement s at time t = 
T at x = 1.5 cm, where T is the period of the oscillations of the wave.
[1]
A student is doing an experiment to determine the speed of sound in air by producing stationary waves inside a horizontal glass tube.
Fine powder is sprinkled inside the tube. A loudspeaker is placed close to the open end of the tube. The other end of the tube is closed. The loudspeaker is connected to a signal generator producing a frequency of 2.72 kHz. The powder inside the tube forms piles at certain locations inside the tube, see Fig. 16.2.
Suggest why the powder piles up at the nodes within the tube.
[1]
Determine the fundamental (minimum) frequency f0 of the stationary wave that can be formed within this tube.
[2]
A light-emitting diode (LED) can be used to determine the Planck constant h. When the LED just starts to emit light, the equation below is valid
where V is the potential difference (p.d.) across the LED, 
is the wavelength of the light emitted, c is the speed of light in vacuum and e is the elementary charge.
In the equation above, 
is the energy of a photon emitted from the LED.
Determine the S.I. base units for h.
[2]
* Describe how an experiment can be carried out in the laboratory to determine h from a graph. Your description must include how V and 
are accurately determined. Assume that the
values of e and c are known.
Additional answer space if required
[6]
Compare the e.m.f. of the battery and the potential difference (p.d.) across the variable resistor in terms of energy transfers or changes.
[1]
State which physical quantity of the variable resistor is changed to alter its resistance.
[1]
A student connects up the circuit above to determine r.
The student varies R and measures the current I. The student plots a graph of 
against R.
1 Use the graph to determine the power dissipated in the variable resistor when
2 The e.m.f. E of the battery is 5.0 V.
Determine r from the intercept of the line with the vertical axis.
[4]
Calculate the work function of potassium in eV.
[3]
This question is about a photoelectron emitted perpendicular to plate E and with an initial kinetic energy of 4.8 × 10–20 J.
Show that the magnitude of deceleration of this photoelectron is 8.8 × 1012 m s–2. (i)
[3]
Show that the initial speed of the photoelectron is about 3 × 105 m s–1. (ii)
[2]
Calculate the time t taken by the photoelectron to travel from plate E to plate C.
[2]
Using the axes shown below, sketch a graph of kinetic energy Ek against distance x from plate E.
[2]
Explain, in terms of photons, what happens to the ammeter reading when light of frequency greater than 6.3 × 1014 Hz is now incident on plate E.
[2]
Deuterium is an isotope of hydrogen. A nucleus of deuterium has a proton and a neutron.
Describe the nature and range of the two forces acting between these two hadrons.
[4]
The diagram below shows two insulated-copper coils A and B connected in circuits.
Both coils are individually wrapped around the same iron rod. Coil A is connected to a cell and a switch. Coil B is connected to a filament lamp.
The switch is initially closed and the lamp is off.
The switch is then opened. The lamp flashes on for a brief time, and then remains off.
Explain these observations in terms of magnetic flux.
[3]
A student is carrying out an experiment using a search coil.
A long solenoid is connected to an alternating current supply.
The search coil is placed at one end of the solenoid. The plane of the search coil is tilted such that it makes an angle 
with the central axis of the solenoid. The maximum alternating induced electromotive force (e.m.f.) across the ends of the search coil is E0.
Name an instrument that can be used to determine E0.
[1]
The equation for E0 is:
E0 = K I0ANf sin 
where I0 = maximum current in the solenoid, A = cross-sectional area of the search coil, N = number of turns of the search coil, f = frequency of the alternating current in the solenoid and K = 4.0 × 10–3 V A–1 m–2 s.
The magnitude of the induced e.m.f. in the search coil can be determined using Faraday’s law of electromagnetic induction:
e.m.f. = rate of change of magnetic flux linkage
In the experiment, angle 
is changed and E0 measured.
Suggest the quantity, or quantities, in the equation E0 = K I0ANf sin 
linked to
1 the ‘rate’ part of the law
2 the ‘change of magnetic flux linkage’ part of the law.
[2]
The student plots a straight-line graph of E0 against sin 
.
Determine f, including the absolute uncertainty. Write your value of f to 2 significant figures.
I0 = (8.0 ± 0.2) A
f =........ ±........ Hz
[4]
The student decides to plot T against R to obtain a straight-line graph.
Show that the line has gradient = C ln2.
[2]
The data points plotted by the student are shown below.
1 Draw a best-fit straight line through the data points and use the gradient of this line to determine C.
2 Use your answer in (ii)1 to calculate the permittivity 
of the paper.
=........ F m–1
[5]
A gamma camera has several important components including a collimator, scintillator and photomultiplier tubes.
Suggest why the collimator needs to be long and narrow.
[1]
State the function of the scintillator.
[1]
In a single photomultiplier tube, a photon of light produces a 0.32 
A pulse of current for a duration of 1.2 ns.
Calculate the number of electrons responsible for this pulse of current.
[2]
State one diagnostic application of a gamma camera.
Question 24 is on the next page
[1]
Describe, in terms of X-ray photons, the attenuation mechanism of Compton scattering.
[2]
Use the graph to determine the exposure time t for the total radiant energy incident per cm2 at a depth of 1.0 cm to be 2.6 J.
[3]
Beyond x = 1.0 cm, the tissue has a larger attenuation coefficient than the value calculated in (i).
On Fig. 24.2, sketch the variation of I with x beyond x = 1.0 cm.
[2]
The paper as printed
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