OCR A Level Physics A Exploring Physics June 2017 question paper H556/02

The diagram below shows the motion of positive and negative particles in a conducting solution.

Which statement is correct?

A The current in the solution is zero.

B The conventional current is to the left.

C The positive particles are always protons.

D The negative particles are always electrons.

Your answer

Which is not a unit of energy?

A kW h

B eV

C J

D W

Your answer

A circuit is shown below.

The battery has negligible internal resistance. The temperature of the NTC thermistor is decreased.

Which of the following statements is/are correct?

1 The current at X increases. 2 The current at Y remains the same. 3 The potential difference across the thermistor increases.

A 1, 2 and 3

B Only 2 and 3

C Only 3

D Only 2

Your answer

A progressive wave of amplitude a has intensity I. This wave combines with another wave of amplitude 0.6 a at a point in space. The phase difference between the waves is 180°.

What is the resultant intensity of the combined waves in terms of I ?

A 0.16 I

B 0.4 I

C 1.6 I

D 2.6 I

Your answer

Stationary waves are produced in a tube closed at one end and open at the other end. The fundamental frequency is 120 Hz.

What is a possible frequency of a harmonic for this tube?

A 60 Hz

B 240 Hz

C 360 Hz

D 480 Hz

Your answer

The graph below shows the variation of potential difference V with charge Q for a capacitor.

Which row is correct for the gradient of the graph and the area under the graph?

Your answer

A capacitor discharges through a resistor. At time t = 0, the charge stored by the capacitor is 600 C. The capacitor loses 5.0 % of its charge every second.

What is the charge left on the capacitor at time t = 4.0 s?

A 111 C

B 120 C

C 480 C

D 489 C

Your answer

Two isolated parallel capacitor plates have an equal and opposite charge. The separation between the plates is doubled. The charge on each plate remains the same but the potential difference between the plates doubles.

Which statement is correct?

A The capacitance of the capacitor doubles.

B The energy stored by the capacitor is halved.

C The permittivity of free space doubles.

D The electric field strength between the plates remains the same.

Your answer

Which statement is correct?

A Hadrons are made up of protons and neutrons.

B A positron and a proton are examples of leptons.

C The positron and the electron have the same mass.

D The weak nuclear force is responsible for alpha-decay.

Your answer

An electron moves in a circle of radius 2.0 cm in a uniform magnetic field of flux density 170 mT.

What is the momentum of this electron?

Your answer

A proton collides with a stationary oxygen-18 nucleus. The collision produces a fluorine-18 nucleus and particle X.

What is particle X?

A neutron

B proton

C electron

D positron

Your answer

A beam of charged particles is not deflected when it passes through a region where both electric and magnetic fields are present.

Which statement is not correct?

A All the particles have the same speed.

B The resultant force on each particle is zero.

C The magnetic force is equal to the electric force on each particle.

D The magnetic field and the electric field are in the same direction.

Your answer

There are four important attenuation mechanisms by which X-ray photons may interact when they pass through matter.

In which mechanism is the X-ray photon scattered with a longer wavelength?

A simple scattering

B Compton effect

C pair production

D photoelectric effect

Your answer

A ray of monochromatic light is incident at the boundary between two transparent materials of refractive index n₁ and n₂. The critical angle is equal to 80°.

A 0.17

B 0.98

C 1.02

D 5.76

Your answer

State the principle of superposition of waves.

Fig. 16.1 shows an arrangement to demonstrate the interference of monochromatic light.

Coherent blue light from a laser is incident at a double-slit. The separation between the slits is 0.25 mm. A series of dark and bright lines (fringes) appear on the screen. The screen is 4.25 m from the slits. Fig. 16.2 shows the dark and bright fringes observed on the screen.

The pattern shown in Fig. 16.2 is drawn to scale.

Use Fig. 16.2 to determine accurately the wavelength of the blue light from the laser.

The blue light is now replaced by a similar beam of red light. State and explain the effect, if any, on the fringes observed on the screen.

State one S.I. base quantity other than length, mass and time.

Show that the total resistance R of the wires is given by the equation

A student uses the equation in (i) to determine R. The table below shows the data recorded by the student in her lab book.

Quantity	Value
	4.7 10−7 m
L	9.5 ± 0.1 cm
d	0.270 ± 0.003 mm

1. Name the likely instruments used by the student to measure L and d.

2. Use the data in the table and the equation in (i) to determine R and the absolute uncertainty. Write your answer to the correct number of significant figures.

3. The instrument used to measure d has a zero-error. The measured d is much larger than the actual value. Discuss how the actual value of R compares with the value calculated above.

Fig. 18.1 shows a circuit.

The cell has e.m.f. 1.5 V. The cell and the variable power supply both have negligible internal resistance.

The e.m.f. of the power supply is set at 4.2 V. Calculate the current I in the 33 resistor.

The e.m.f. of the variable supply is now slowly decreased from 4.2 V to 0 V. Describe the effect on the current I in the 33 resistor.

* A group of students are investigating the power dissipated in a variable resistor connected across the terminals of a cell. The cell has e.m.f. 1.5 V. The students determine the power P dissipated in the variable resistor of resistance R.

Fig. 18.2 shows the data points plotted by the students on a graph of P (y-axis) against R (x-axis).

The group of students know that maximum power is dissipated in the variable resistor when R is equal to the internal resistance r of the cell.

Describe, with the help of a suitable circuit diagram, how the students may have determined P and R. Use Fig. 18.2 to estimate the internal resistance r of the cell and discuss any limitations of the data plotted by the group.

Electromagnetic radiation is incident on a negatively charged zinc plate. Electrons are emitted from the surface of the plate when a weak intensity ultraviolet source is used. Electrons are not emitted at all when an intense visible light from a lamp is used.

Explain these observations.

The maximum wavelength of the electromagnetic radiation incident on the surface of a metal which causes electrons to be emitted is 2.9 10⁻⁷ m.

Calculate the maximum kinetic energy of electrons emitted from the surface of the metal when each incident photon has energy of 5.1 eV.

Fig. 20.1 shows a positively charged metal sphere and a negatively charged metal plate.

On Fig. 20.1, draw a minimum of five electric field lines to show the field pattern between the

sphere and the plate.

Define electric potential at a point in space.

A metal sphere is given a positive charge by connecting its surface briefly to the positive terminal of a power supply. The electric potential at the surface of the sphere is + 5.0 kV. The sphere has radius 1.5 cm.

A capacitor of capacitance 7.2 pF consists of two parallel metal plates separated by an insulator of thickness 1.2 mm. The area of overlap between the plates is 4.0 10⁻⁴ m². Calculate the permittivity of the insulator between the capacitor plates.

permittivity =........ F m⁻¹

Fig. 21 shows a circuit.

The capacitance of each capacitor is 1000 F. The resistance of the resistor is 10 k. The cell has e.m.f. 1.5 V and negligible internal resistance.

Calculate the total capacitance C in the circuit.

C =........ F

The switch S is closed at time t = 0. There is zero potential difference across the capacitors at t = 0. Calculate the potential difference V across the resistor at time t = 12 s.

* A student conducts an experiment to confirm that the uniform magnetic flux density B between the poles of a magnet is 30 mT.

A current-carrying wire of length 5.0 cm is placed perpendicular to the magnetic field.

The current I in the wire is changed and the force F experienced by the wire is measured. Fig. 22.1 shows the graph plotted by the student.

The student’s analysis is shown on the graph of Fig. 22.1 and in the space below.

F = BIL

This is just 2 mT out from the 30 mT value given by the manufacturer, so the experiment is very accurate.

Evaluate the information from Fig. 22.1 and the analysis of the data from the experiment. No further calculations are necessary.

Use Faraday’s law of electromagnetic induction to explain why the filament lamp is lit.

The primary coil has 400 turns and the secondary coil has 20 turns. The potential difference across the lamp is 12 V and it dissipates 24 W. The transformer is 100% efficient.

1. Calculate the current in the primary coil.

2. The alternating voltage supply is replaced by a battery and an open switch in series. The switch is closed. The lamp is lit for a short period of time and then remains off. Explain this observation.

Describe the nature of the strong nuclear force.

Name a hadron found in the nucleus of an atom and state its quark combination.

name of hadron:........ quark combination:........

Write a decay equation in terms of a quark model for beta-minus decay.

Stars produce energy by nuclear fusion. One particular fusion reaction between two protons (¹₁H) is shown below.

In this reaction 2.2 MeV of energy is released.

Only one of the particles shown in the reaction has binding energy. Determine the binding energy per nucleon of this particle. Explain your answer.

Explain why high temperatures are necessary for fusion reactions to occur in stars.

A gamma photon in a star can spontaneously create an electron-positron pair. Calculate the maximum wavelength of a gamma photon for this creation event.

Fluorine-18 is a common radioactive isotope used in positron emission tomography (PET). Fluorine-18 emits positrons. A patient is injected with a radiopharmaceutical containing fluorine-18.

Describe how a PET scanner is used to locate an area of increased activity within the patient.

The half-life of fluorine-18 is 110 minutes. Calculate the time t in minutes for the activity of the radiopharmaceutical to decrease to 30% of its initial activity.

PET scanners are not available in all hospitals. This is because fluorine-18 requires expensive on-site particle accelerators and fluorine-18 has a very small ‘shelf-life’. Suggest the impact this may have on the treatment and diagnosis of patients in the country.