Marr College Physics Higher Physics

Particles and Waves - Homework

• Home learning is a vital part of your education

• The following will have a positive impact on your learning, progress and overall level of attainment

– Spending at least the same amount of time and care on homework questions that you would in class

– Completing all questions to the best of your ability for the due date

– Answering the questions with your notes beside you to consult if you are stuck

– Using the time between homework being issued and hand-in to ask your teacher for help

– Self-assessing using the numerical answers provided • If you get the same answer as the file, you feel good and your confidence

develops

• If you get a different answer, it allows you to go back and look at your working and try to spot and correct mistakes

• If you still can’t see what is wrong, ask your teacher

– Responding positively to feedback provided by your teacher and using the advice to improve

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Relationships Required for Higher Physics

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1. Copy and complete the table by placing the fermions in the list below in the correct column of the table.

2. a) State the difference between a hadron and a lepton in terms of the type of

force experienced by each particle. b) Give one example of a hadron and one example of a lepton. 3. Information on the sign and charge relative to proton charge of six types of

quarks (and their corresponding antiquarks) is shown in the table. a) Calculate the charge of the following combinations of quarks:

i. two up quarks and one down quark ii. one up quark and two down quarks iii. two antiup quarks and one antidown quark iv. one antiup quark and two antidown quarks.

b) Name the force which holds the quarks together in protons and neutrons. End of Exercise 1

Homework 1 – The Standard Model

Quarks Leptons

bottom charm down electron strange electron neutrino muon muon neutrino

tau tau neutrino top up

Quark name Charge relative

to size of proton

charge

Antiquark name Charge relative

to size of proton

charge

up +2/3 antiup –2/3

charm +2/3 anticharm –2/3

top +2/3 antitop –2/3

down –1/3 antidown +1/3

strange –1/3 antistrange +1/3

bottom –1/3 antibottom +1/3

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1. Draw the electric field around the following charges. You must show the direction of the field clearly.

a) b)

2. What is the definition of a volt?

3. Look at the following diagram.

a) What is the potential difference between the two plates? b) Calculate the work done in moving the charged particle across the electric field.

4. The diagram shows an arrangement which is used to accelerate electrons. The potential difference between the cathode and anode is 2.5 kV. Assuming the electrons start from rest, calculate the speed of the electron as it

reaches the anode.

End of Exercise 2

Homework 2 – Forces on Charged Particles

+ -

300 V 100 V

1.5 C

+ -

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In the following questions, when required, use the following data:

Charge on electron = –1·60 × 1019 C Mass of electron = 9·11 × 1031 kg Charge on proton = 1·60 × 1019 C Mass of proton = 1·67 × 1027 kg

1. In an evacuated tube, an electron initially at rest is accelerated through a p.d. of

500 V.

a) Calculate, in joules, the amount of work done in accelerating the electron.

b) How much kinetic energy has the electron gained? c) Calculate the final speed of the electron.

2. The diagram below shows the basic features of a proton accelerator.

It is enclosed in an evacuated chamber.

Protons are released from the proton source and start at rest at P. A potential difference of 200 kV is maintained beteween P and Q.

a) Calculate the work done on a proton as it is accelerated from P to Q. b) The speed of a proton as it reaches Q c) The distance between P and Q is now halved. What effect, if any, does this change have on the speed of a proton as it reaches Q. You must justify your answer.

End of exercise 3

Homework 3 – Particle Accelerators

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1. There are three isotopes of hydrogen:

a) How many protons does each nucleus have? b) How many neutrons does each nucleus have?

2. Energy is produced within the Sun by fusion reactions.

a) State what is meant by a fusion reaction. b) Explain briefly why a fusion reaction releases energy.

3. The Sun is the source of most of the energy on Earth. This energy is produced by

nuclear reactions which take place in the interior of the Sun. One such reaction can be described by the following statement:

𝐻 + 𝐻 → 𝐻𝑒 + 𝑛01

𝑿4

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a) Name this type of nuclear reaction b) Calculate the missing number X. c) Using information from the table below, calculate the energy released in

this reaction.

End of Exercise 4

Homework 4 – Fission and Fusion

H 1 1 H

2 1 H

3 1

Particle Mass (kg)

𝐻 13 5.005 10-27

𝐻 12 3.342 10-27

𝐻𝑒 𝑿4 6.642 10 -27

𝑛01 1.675 10-27

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1. When introducing the photoelectric effect a Physics teacher writes:

‘One of the important factors affecting photoelectric emission from a metal is the threshold frequency for the metal.’

Explain the meaning of the terms:

a) photoelectric emission; b) threshold frequency.

2. Red light has a wavelength of 6·44 × 107 m. Calculate the energy of one photon of this light. 3. For a certain metal, the energy required to eject an electron from an atom is 3 x

10-19 J.

a) What is the minimum frequency of electromagnetic radiation required to produce the photoelectric effect with this metal?

b) The metal is illuminated with blue light that has a wavelength of 400 nm. Show by calculation that this will cause the photoelectric effect to

occur. c) Calculate the kinetic energy that the ejected electrons will have when the

metal is illuminated with this light.

End of Exercise 5

Homework 5 – Photoelectric Effect

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1. An experiment is set up to investigate interference effects and a pattern of dark and bright fringes is produced.

Explain, in terms of waves, how the pattern of bright and dark fringes are produced.

2. Microwaves are passed through two slits, A and B, in a metal plate as shown in the diagram below.

A microwave detector is moved along a straight line from X to Y. The first

minimum of microwave intensity is detected at point P. The distance AP is 41 cm and BP is 43 cm.

Find the wavelength of the microwaves. 3. A grating with 300 lines/mm is used with a spectrometer and a source of

monochromatic light to view an interference pattern as shown below. The second maximum of interference is observed when the telescope is at an

angle of 24.5o. Calculate the wavelength of the light. 4. A grating or a prism can be used to produce spectra from a source of white light. Give two differences between the spectra obtained using the grating and the

prism. Diagrams may be used to illustrate your answer.

End of Exercise 6

Homework 6 – Interference

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1. A ray of red light has a wavelength of 700 nm in air. It is incident on a block of plastic, and is refracted as shown below:

a) Calculate the refractive index of the block of plastic. b) What is the wavelength of the red light in the block of plastic? c) A blue light now replaces the red light. What happens to the angle of refraction?

2. Diamond sparkles in sunlight because it has a high refractive index. The high refractive index that diamond has means that the critical angle for

diamond is low.

a) What is meant by ‘critical angle’? b) The refractive index of diamond is 2.42.

Calculate the critical angle.

3. White light is shone onto a triangular glass prism. A spectrum is viewed on the

other side of the prism.

a) Why is a spectrum produced? b) List the colours in order from most deflected to least deflected.

End of Exercise 7

Homework 7 – Refraction

55°

35°

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1. A light meter is used to measure the irradiance of light from a small lamp At a distance of 1.5 m from the lamp, the irradiance of the light is 0.60 Wm-2. What is the irradiance at a distance of 4.5 m from the lamp? At a distance of 1.5 m from a laser, the irradiance of the laser light is 400 Wm-2. What is the irradiance at a distance of 4.5 m from the laser? 2. The following diagram represents the energy levels of a particular metal’s atoms.

a) How many possible transitions are there for this atom? b) Calculate the maximum frequency of light absorbed by this atom. c) Which part of the spectrum would this absorption line be found in?

Explain your answer.

3. Explain why the absorption spectrum of an atom has dark lines corresponding to frequencies present in the emission spectrum of the atom.

4. A laser used in a CD player emits monochromatic light of wavelength 840 nm.

a) When the light passes through a grating only one bright line is seen in the spectrum. Explain why only one line appears in the emission spectrum of the laser.

b) Calculate the difference in energy between the two energy levels that produce photons with this wavelength.

End of Exercise 8

Homework 8 – Spectra

-5 x 10-19 J

-9 x 10-19 J

-16 x 10-19 J

-25 x 10-19 J

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• Each of these exercises consist of both multiple choice and long answer questions.

• All of these questions are of the same standard as those in the final exam.

• Your teacher will issue these at the end of each key area(s) and give you plenty

of time to complete the questions • You are also able to ask for help before the hand-in date

• Numerical answers are provided – therefore you should be able to self-assess

• Check your answers, spot mistakes and fix

• You are therefore expected to attempt and complete all questions and hand in for the agreed deadline

Exam-standard Exercises

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1. Hadrons are composite particles made of quarks. Up (u) quarks have a charge of + ⅔ e whilst down (d) quarks have a charge of - ⅓ e, where e is equal to the magnitude of an electron’s charge. Antiquarks have the opposite charge to these values.

Which line in the following table of data on hadrons is correct? 2. Two parallel metal plates X and Y in a vacuum have a potential difference V

across them. An electron of charge e and mass m, initially at rest, is released from plate X. The speed of the electron when it reaches plate Y is given by A 2eV/m B √(2eV/m) C √(2V/em) D 2V/em E 2mV/e

Exam-Standard Exercise A

Hadron Quark

structure Charge (e)

A Proton udd +1 B Proton ddd +1 C Neutron uū 0 D Neutron uud +1 E Neutron udd 0

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3. The diagram below shows a circuit with a 6.0 V battery connected to two parallel metal plates A and B which are 0.30 m apart.

The amount of work needed to move 2 C of charge from plate A to B is A 1.8 J B 3.0 J C 6.0 J D 12.0 J E 20.0 J

4. Which row in the table shows an example of a hadron, lepton and boson?

+ + + + +

+ + + + +

+ + + + + + + + + +

Direction of proton

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5. A particle accelerator increases the speed of protons by accelerating them between a pair of parallel metal plates, A and B, connected to a power supply as shown below.

The potential difference between A and B is 25 kV. a) Show that the kinetic energy gained by a proton between plates A and B is 4.0 x 10-15 J b) The kinetic energy of a proton at plate A is 1.3 x 10-16 J. Calculate the velocity of the proton on reaching plate B. c) The plates are separated by a distance of 1.2 m. Calculate the force produced by the particle accelerator on a proton as it travels between plates A and B. d) Protons can be detected by their deflection in a magnetic field.

Copy and complete the diagram below, showing clearly the path of a proton as it passes into the magnetic field.

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6. Sub-atomic particles can be either hadrons or leptons. a) State one difference between these two groups of particles. b) Give an example of a hadron and an example of a lepton. c) Hadrons can be further divided into two groups. Name these two groups

and state a difference between them. d) A conversation is overheard between two young pupils who are discussing

their science lessons. Pupil A “We learned in science today that the nucleus of an atom is made of protons which are positively charged and neutrons which have no charge.” Pupil B “That’s interesting because we learned in science that like charges

repel. How come the protons in the nucleus don’t fly apart?” Pupil A “I don’t know.” Write a paragraph that would explain to the pupils why the protons in a nucleus do not fly apart.

7. In a famous experiment to investigate the structure of the atom, a beam of

radiation is directed at a thin, gold foil target as shown in the diagram below. The experiment shows that most of the radiation passes through the gold foil

but some “bounces back” without passing through the foil. a) State the type of radiation used. b) Explain how the results of the experiment suggest that the mass of the

atom is concentrated at its centre.

End of Exam-Standard Exercise A

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1. To demonstrate the photoelectric effect, radiation is directed onto the surface of a clean charged zinc plate.

Which of the following sets of conditions is required to produce the emission of photoelectrons from the zinc plate?

2. An element X emits an alpha particle to form a new element. Which of the following statements is/are correct about this new element? I The total number of protons and neutrons is 4 less than in element X. II The number of protons is the same as element X. III The new element is an isotope of element X. A I only B II only C III only D I and III only E II and III only 3. The minimum energy required to eject an electron from a certain metal is 3.0 x

10-19 J. Light of frequency 4.8 X 1014 Hz is incident on this metal. Which of the following statements is correct? A Electrons will not be ejected from the metal. B Electrons will be ejected with 0 J of kinetic energy. C Electrons will be ejected with 1.8 x 10-20 J of kinetic energy. D Electrons will be ejected with 3.2 x 10-19 J of kinetic energy. E Electrons will be ejected with 6.2 x 10-19 J of kinetic energy.

Exam-Standard Exercise B

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4. Ultraviolet radiation is incident on a zinc plate. Photoelectrons with a certain maximum kinetic energy are released from the zinc. The irradiance of the ultraviolet radiation is now increased.

What happens to the maximum kinetic energy of the photoelectrons and the rate at which they are released?

5. The three statements below refer to the fission process. I Fission may be spontaneous. II Fission can be produced when neutrons bombard a nucleus, which has a

large mass number. III When fission occurs, a nucleus with a large mass number may split into

nuclei with smaller mass numbers, along with several neutrons. Which statements is/are true? A III only B I only II only C I and III only D II and III only E I, II and III

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6. It is quoted in a text book that “the work function of caesium is 3.04 x 10-19J” a) Explain what is meant by the above statement. b) In an experiment to investigate the photoelectric effect, a glass vacuum

tube is arranged as shown below. The tube has two electrodes, one of which is coated with caesium. Light of frequency 6.1 x 1014 Hz is shone on to the caesium coated

electrode. (i) Show that the maximum kinetic energy of a photoelectron leaving the

caesium coated electrode is 1.0 10-19 J.

(ii) An electron leaves the caesium coated electrode with this maximum kinetic energy.

Calculate its kinetic energy as it reaches the upper electrode when the p.d. across the electrodes is 0.8 V.

c) The polarity of the supply voltage is now reversed. Calculate the minimum voltage which should be supplied across the

electrodes to stop photoelectrons from reaching the upper electrode.

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7. The following statement represents a nuclear reaction which may form the basis of a nuclear power station of the future.

a) State the name given to the above type of nuclear reaction. b) Explain, using E = mc2, how this nuclear reaction results in the production

of energy. c) Using the information given below, and any other data required from the

Data Sheet, calculate the energy released in the above nuclear reaction. d) Calculate how many reactions of the type represented above would occur

each second to produce a power of 25 MW.

8. The first three stages in a radioactive decay series are shown below. a) What particle is emitted when Thorium (Th) decays to Palladium (Pa)? b) How many neutrons are in the nuclide represented by ? c) In the next stage of the above decay series, an alpha particle is emitted.

Copy and complete this stage of the radioactivity decay series shown below, giving values for a, b, c and d, and renaming the element X.

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9. The apparatus shown below is used to investigate photoelectric emission from the metal surface, X, when electromagnetic radiation is shone on the surface.

The frequency of the electromagnetic radiation can be varied. a) When radiation of a certain frequency is shone on the metal surface X, a

reading is obtained on the ammeter. Sketch a graph to show how the current in the circuit varies with the

irradiance of the radiation. b) Explain why there is no reading on the ammeter when the frequency of the

radiation is decreased below a particular value.

End of Exam-Standard Exercise B

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1. Light of frequency 6 x 1014 Hz passes from air to glass. The refractive index of the glass is 1.5 and the speed of light is 3 x 10 8 ms-1.

The wavelength of this light in the glass is A 5.0 x 10-9 m B 3.3 x 10-7 m C 5.0 x 10-7 m D 7.5 x 10-7 m E 1.8 x 1023 m 2. A space probe is positioned 3 x 1011 m from the Sun. It needs solar panels with

an area of 4 m2 to absorb sufficient energy from the Sun to keep it functioning correctly.

What area of solar panels would be needed to keep the probe functioning correctly if it is to be repositioned at a distance of 6 x 1011 m from the Sun?

A 1 m2 B 2 m2 C 4 m2 D 8 m2 E 16 m2 3. Which row in the following table gives the approximate wavelengths of red,

green and blue light in nanometres?

Exam-Standard Exercise C

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4. The diagram below shows some of the energy levels for the hydrogen atom. The highest frequency of radiation emitted due to a transition between two of

these energy levels is A 2.04 x 1020 Hz B 1.63 x 1020 Hz C 3.08 x 1015 Hz D 2.46 x 1015 Hz E 1.59 x 1014 Hz 5. A microwave transmitter is directed at a metal plate which has two slits P and Q

in it as shown. The microwave radiation emitted has a wavelength of 3 cm.

A microwave receiver is moved from R to S and, in doing so, detects maxima and

minima of intensity at the positions shown. What is the path difference between PR and QR? A 1.5 cm B 3.0 cm C 4.5 cm D 6.0 cm E 9.0 cm

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6. A biologist is studying the effect of different colours of light on a sample of chlorophyll.

The biologist sets up the apparatus shown below, using a diffraction grating with 6.0 x 105 lines per metre to produce a first order spectrum of sunlight.

a) Explain briefly how a diffraction grating produces a continuous spectrum

from the ray of sunlight. b) (i) The wavelength of the light at the end X of the spectrum is 410 nm.

Calculate the value of the angle q. (ii) The angle A, in the diagram above, is 9°. Calculate the wavelength at

end Y of the spectrum. c) The biologist now uses a triangular glass prism to produce a continuous

spectrum from a ray of sunlight. State two differences between this spectrum and the spectrum produced

by the grating.

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7. The line emission spectrum of hydrogen has four lines in the visible spectrum as shown in the following diagram.

These four lines are caused by the electron transitions in a hydrogen atom from

high energy levels to a low energy level E2 as shown below. a) From the information above, state which spectral line W, X, Y or Z is

produced by an electron transition from E3 to E2. b) Explain why lines Y and Z in the line emission spectrum are brighter than

the other two lines. c) Infrared radiation of frequency 7.48 x 1013 Hz is emitted from a hydrogen

atom. (i) Calculate the energy of one photon of this radiation. (ii) Show by calculation which electron transition produces this radiation.

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8. Two identical loudspeakers X and Y are set up in a room which has been designed to eliminate the reflection of sound. The loudspeakers are connected to the same signal generator as shown.

a) When a sound level meter is moved from P to T, maxima and minima of

sound intensity are detected. Explain, in terms of waves, why the maxima and minima are produced. b) The sound level meter detects a maximum at P. As the sound level meter is moved from P, it detects a minimum then a

maximum then another minimum when it reaches Q. Calculate the wavelength of the sound used. End of Exam-Standard Exercise C

Numerical Answers

Exercise 2

3. (b) 300 J

4. 2.96 107 ms-1

Exercise 3

1. (a) 8 10-17 J

(c) 1.33 107 ms-1

2. (a) 3.2 10-14 J

(b) 6.2 106 ms-1

Exercise 4

3. (c) 2.7 10-12 J

Exercise 5

2. 3.09 10-19 J

3. (a) 4.5 1014 Hz

(b) Show that either work function = 4.97 10-19 J or threshold frequency = 7.5 1014 Hz

(c) 1.97 10-19 J

Exercise 6

2. 4 cm

3. 6.90 10-7 m

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Numerical answers

Exercise 7

1. (a) 1.43

(b) 490 nm

2. (a) 24°

3. (a) 0.98 J

(b) 0.98 J

(c) 1.98 m s-1

Exercise 8

1. 0.11 Wm-2

2. (b) 2.26 1015 Hz

(c) 1.33 10-7 m

4. (b) 2.37 10-19 J

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Numerical answers

Exam Standard Exercise A

5. (a) 4.0 10-15 J

(b) 2.22 106 ms-1

(c) 3.33 10-15 N

Exam Standard Exercise B

6. (b) (i) 1.0 10-19 J

(ii) 2.28 10-19 J

(c) 0.625 V

7. (c) 2.89 10-12 J

(d) 8.67 1018 reactions per second

Exam Standard Exercise C

6. (a) 41°

6. (b) (i) 14.2°

(ii) 6.58 10-7 m

7. (c) (i) 4.96 10-20 J

8. (b) 0.8 m

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