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EXAMINATION QUESTIONS (6)

1. What is a beta-particle? A a helium nucleus B a high-energy electron C four protons D two neutrons

2. The diagram shows part of a circuit used to switch street lamps on and off automatically.

What is the effect on the light-dependent resistor

(LDR) when it gets dark?

3. An alternating potential difference (p.d.) is applied to the Y-plates of a cathode-ray oscilloscope. The time-base is turned off. Which of the following patterns would appear on the screen?

4. 22

10Ne represents an atom of neon. How many neutrons does it have? A) 10

B) 12

C) 22

D) 32

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5. The diagram shows a radioactivity experiment.

When a piece of paper is used as the absorber, the count rate drops to the background count rate. What radiation is the source emitting?

A) alpha only B) beta only C) gamma only D) alpha, beta and gamma

6. Fig. 9.1 shows a beam of electrons, two charged plates and a screen. These components are inside an electron tube, the outline of which is not shown.

The beam of electrons hits the screen at the point P. (a) On Fig. 9.1, (i) complete the path of the electron beam, (ii) mark the charges on both plates, (iii) mark with an arrow and the letter C the direction of the conventional current in the electron beam. (b) In this electron tube, the electrons are produced at X and are accelerated towards Y. In the space below, draw a labelled diagram of the components needed to produce and accelerate the electrons. 7. Charged particles are emitted from the cathode of an oscilloscope. What is the name and charge of these particles?

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8. A radioactive source emits radiation that can pass through a sheet of paper but not through thick aluminium. What does this show about the radiation?

A) It is alpha-particles. B) It is beta-particles. C) It is gamma-rays. D) It is a mixture of alpha-

particles and gamma-rays. 9. A sample of a radioactive isotope is decaying. Which atoms will decay first? A impossible to know, because radioactive decay is random B impossible to know, unless the age of the material is known C atoms near the centre, because they are surrounded by more atoms D atoms near the surface, because the radiation can escape more easily

10. (a) A radioactive isotope emits only αparticles.

(i) In the space below, draw a labelled diagram of the apparatus you would use to

prove that no β-particles or γ-radiation are emitted from the isotope.

(ii) Describe the test you would carry out. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. ..................................................................................................................................

(iii) Explain how your results would show that only α-particles are emitted.

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(b) Fig. 11.1 shows a stream of α-particles about to enter the space between the poles of a

very strong magnet.

Describe the path of the α-particles in the space between the magnetic poles.

.....................................................................................[3]

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11. Which type of radiation can be stopped by a sheet of paper?

A α-particles

B β-particles

C γ-rays

D X-rays 12. The half-life of a radioactive substance is 5 hours. A sample is tested and found to contain 0.48 g of the substance. How much of the substance was present in the sample 20 hours before the sample was tested? A 0.03 g B 0.12 g C 1.92 g D 7.68 g 13. (a) Fig. 9.1 shows the screen of a c.r.o. (cathode-ray oscilloscope). The c.r.o. is being used to display the output from a microphone. The vertical scale on the screen is in volts.

(i) Describe the output from the microphone. ................................................................................................................................. ................................................................................................................................. (ii) Use the graph to determine the peak voltage of the output. ................................................................................................................................. (iii) Describe how you could check that the voltage calibration on the screen is correct. ................................................................................................................................. ................................................................................................................................. (b) Fig. 9.2 shows the screen of the c.r.o. when it is being used to measure a small time interval between two voltage pulses.

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(i) What is the distance on the screen between the two voltage pulses? ................................................................................................................................. (ii) The time-base control of the c.r.o. is set at 5.0ms / cm. Calculate the time interval between the voltage pulses. time = ........................................ (iii) Suggest one example where a c.r.o. can be used to measure a small time interval. .................................................................................................................................

14. (a) A sodium nucleus decays by the emission of a β -particle to form magnesium. (i) Complete the decay equation below. 24Na11 Mg +

(ii) Fig. 11.1 shows β -particles from sodium nuclei moving into the space between the

poles of a magnet.

Describe the path of the β -particles between

the magnetic poles.

.................................................................................................................................

.................................................................................................................................

.................................................................................................................................

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(b) Very small quantities of a radioactive isotope are used to check the circulation of blood by injecting the isotope into the bloodstream. (i) Describe how the results are obtained. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. .................................................................................................................................

(ii) Explain why a γ -emitting isotope is used for this purpose rather than one that

emits either α -particles or β -particles.

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................................................................................................................................. 15. Which particles are emitted during thermionic emission? A electrons B ions C neutrons D protons 16. The equation shows the decay of the nuclide X.

What are the values of P and Q? 16. (a) Fig. 10.1 shows the faces of two ammeters. One has an analogue display and the other a digital display.

State what is meant by the terms analogue and digital. ......................................................................................................................................... ......................................................................................................................................... .....................................................................................................................................[2] (b) (i) Name the components from which logic gates are made. ...............................................................................................................................1] (ii) In the space below, draw the symbol for an AND gate. Label the inputs and the output. [1] (iii) Describe the action of an AND gate with two inputs. [2]

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17. (a) α-particles can be scattered by thin gold foils. Fig. 11.1 shows part of the paths of three α-particles.

Complete the paths of the three α-particles. [3]

(b) What does the scattering of α-particles show about

atomic structure?

.........................................................................................................................................

.........................................................................................................................................

.....................................................................................................................................[2]

(c) State the nucleon number (mass number) of an α-particle.

nucleon number = ………………… [1]

18. A beam of cathode rays passes through an electric field between two parallel plates.

In which direction is the beam deflected?

A into the page

B out of the page

C towards the bottom of the page

D towards the top of the page

19. Which line correctly describes α-particles?

20. A small amount of a radioactive isotope contains 72 billion unstable nuclei. The half-life of the

isotope is 4 hours.

How many unstable nuclei would remain after 12 hours?

A 6 billion

B 9 billion

C 18 billion

D 24 billion

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21. How many nucleons are in a nucleus of

A) 19 B) 20 C) 39 D) 58

22. (a) (i) What is the function of a transistor when placed in an electrical circuit? .................................................................................................................................. (ii) Describe the action of a transistor. .................................................................................................................................. ................................................................................................................................. ................................................................................................................................. (b) (i) In the space below, draw the symbol for an OR gate. Label the inputs and the output. ] (ii) Describe the action of an OR gate that has two inputs. .................................................................................................................................. .................................................................................................................................. ...............................................................................................................................

23. (a) The decay of a nucleus of radium 226 Ra88 leads to the emission of an α-particle and

leaves behind a nucleus of radon (Rn). In the space below, write an equation to show this decay. [2]

(b) In an experiment to find the range of α-particles in air, the apparatus in Fig. 11.1 was

used.

(i) State what causes the count rate 9 cm from the source. .................................................................................................................................. (ii) Estimate the count rate that is due to the source at a distance of 2 cm. ..................................................................................................................................

(iii) Suggest a value for the maximum distance that -particles can travel from the source. .................................................................................................................................. (iv) Justify your answer to (iii).

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24. Which type of radiation has the greatest ionising effect? A α-particles B β-particles C γ-rays

D all have the same ionising effect 25. A powder contains 400 mg of a radioactive material that emits α-particles. The half-life of the material is 5 days. What mass of that material remains after 10 days?

A) 0 mg B) 40 mg C) 100 mg D) 200 mg 26. In the symbol below, A is the nucleon number and Z is the proton number.

What is represented by the symbol? A an electron B a neutron C a nuclide D an X-ray 27. (a) In the space provided, draw the symbol for a NOR gate. Label the inputs and the output. (b) State whether the output of a NOR gate will be high (ON) or low (OFF) when (i) one input is high and one input is low, .................................................................................................................................. (ii) both inputs are high. .................................................................................................................................. (c) Fig. 9.1 shows a digital circuit made from three NOT gates and one NAND gate.

(i) Write HIGH or LOW in each of the boxes on Fig. 9.1. [2] (ii) State the effect on the output of changing both of the inputs. .................................................................................................................................. .............................................................................................................................. [1]

28. A radioactive source emits only -particles.

(a) A scientist wishes to investigate the deflection of -particles by an electric field. Draw a labelled diagram to suggest a suitable experimental arrangement.

(b) State how the apparatus would be used to show the deflection of the -particles by the electric field. ......................................................................................................................................... .........................................................................................................................................

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(c) State how the results would show the deflection of the -particles. ......................................................................................................................................... .................................................................................................................................... [1] (d) Explain the direction of the deflection obtained. ......................................................................................................................................... .................................................................................................................................... [1] 29. (a) Fig. 9.1 shows an a.c. supply connected to a resistor and a diode.

(i) State the effect of fitting the diode in the circuit. .................................................................................................................................. .............................................................................................................................. [1] (ii) On Fig. 9.2, sketch graphs to show the variation of the a.c. supply voltage and the output voltage with time.

(b) (i) In the space below, draw the symbol for a NOT gate. (ii) State the action of a NOT gate. .................................................................................................................................. ..................................................................................................................................

30. (a) Fig. 10.1 is the decay curve for a radioactive isotope that emits only β-particles.

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Use the graph to find the value of the half-life of the isotope. Indicate, on the graph, how you arrived at your value. half-life …………………………. [2]

(b) A student determines the percentage of β-particles absorbed by a thick aluminium sheet. He uses

a source that is emitting only β-particles and that has a long half-life.

(i) In the space below, draw a labelled diagram of the apparatus required, set up to make the determination.

(ii) List the readings that the student needs to take. .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .............................................................................................................................. [3]

31. A radioactive source emits radiation that can pass through a sheet of paper but not through thick aluminium.

What does this show about the radiation? A It is α-particles. B It is β-particles. C It is γ-rays. D It is a mixture of α-particles and γ-rays.

32. Which particles are found in the nucleus of an atom? A neutrons and protons only B neutrons only C protons and electrons only D protons, electrons and neutrons

33. A cathode-ray tube has an anode and an earthed cathode. Which line in the table shows the charge and the temperature of the anode?

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34. The diagram shows five atoms in a radioactive substance. The atoms each give out an α-particle.

Atom 1 is the first to give out a particle. Atom 3 is the second to give out a particle. Which atom will give out the next particle? A atom 2 B atom 4 C atom 5 D impossible to tell

35. A Geiger counter detects radiation from radioactive sources. A radioactive source is inside a thick aluminium container as shown.

Which type of radiation from this source is being detected? A α-particles B β-particles C γ-rays

D radio waves 36. The nucleus of a neutral atom of lithium is represented by 7Li3

How many protons, electrons and neutrons does the atom contain?

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37. (a) Fig. 9.1 shows how a beam of electrons would be deflected by an electric field produced between two metal plates. The connections of the source of high potential difference are not shown.

(i) On Fig. 9.1, draw in the missing connections. (ii) Explain why the beam of electrons is deflected in the direction shown. In your answer, consider all the charges involved and their effect on each other. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. (b) The deflection of a beam of electrons by an electric field is used in cathode-ray oscilloscopes. (i) What makes the electron beam move backwards and forwards across the screen? ................................................................................................................................. ................................................................................................................................. (ii) What makes the electron beam move up and down the screen? ................................................................................................................................. ................................................................................................................................. An a.c. waveform is displayed so that two full waves appear on the screen of a cathoderay oscilloscope. Fig. 9.2 shows the face of the oscilloscope. On Fig. 9.2, draw in the waveform.

38. Fig. 10.1 shows a circuit that is used to switch on a lamp automatically when it starts to go dark.

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(a) Write down the names of the components labelled A, B, C and D. A ........................................... B ........................................... C ........................................... D ........................................... [2] (b) Which of the four components A, B, C or D acts as a switch? ........................ (c) Explain why the lamp comes on as it goes dark. ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... .....................................................................................................................................[3]

39. (a) α-particles, β-particles and γ-rays are known as ionising radiations.

(i) Describe what happens when gases are ionised by ionising radiations. ................................................................................................................................. ................................................................................................................................. .................................................................................................................................

(ii) Suggest why -particles are considered better ionisers of gas than -particles. ................................................................................................................................. ................................................................................................................................. [3] (b) (i) Suggest two practical applications of radioactive isotopes. 1. .............................................................................................................................. 2. .............................................................................................................................. (ii) For one of the applications that you have suggested, describe how it works, or draw a labelled diagram to illustrate it in use. ................................................................................................................................. ................................................................................................................................. .................................................................................................................................

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40. Particles are emitted by a heated cathode in a cathode-ray tube.

What are these particles? A atoms B electrons C neutrons D protons

41. Which line in the table describes the nature of an α-particle and of a γ-ray?

42. The count rates of four radioactive sources were measured at the same time on three consecutive days. Which source has a half-life of two days?

43. Which statement is true of all neutral atoms? A The number of electrons equals the number of nucleons. B The number of neutrons equals the number of protons. C The number of nucleons equals the number of neutrons. D The number of protons equals the number of electrons.

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44. There are three nuclides of hydrogen.

Which of these nuclides have the same number of protons in their nuclei? A 1 and 2 only B 2 and 3 only C all of them D none of them 45. Fig. 10.1 shows a circuit based on a transistor and a thermistor.

(a) Describe the action of the thermistor in this circuit. ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ................................................................................................................................... [3] (b) State and explain how the circuit may be modified so that the lamp switches on at a different temperature. ......................................................................................................................................... ......................................................................................................................................... ................................................................................................................................... [2] (c) State one practical use of this circuit. ................................................................................................................................... [1]

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46. Fig. 11.1 shows the paths of three α-particles moving towards a thin gold foil.

Particle A is moving directly towards a gold nucleus. Particle B is moving along a line which passes close to a gold nucleus. Particle C is moving along a line which does not pass close to a gold nucleus.

(a) On Fig. 11.1, complete the paths of the -particles A, B and C. [3]

(b) State how the results of such an experiment, using large numbers of -particles,

provides evidence for the existence of nuclei in gold atoms. ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ................................................................................................................................... [3] 47. The diagram shows a cathode-ray tube.

What must be done to deflect the electron beam upwards? A make X1 more positive than X2

B make X2 more positive than X1

C make Y1 more positive than Y2

D make Y2 more positive than Y1

48. A sheet of paper is placed between a radioactive source and a detector.

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Which types of radiation can pass through the paper?

A α-particles and β-particles only

B α-particles and γ-rays only

C β-particles and γ-rays only

D α-particles, β-particles and γ-rays

49. A sample of radioactive isotope is decaying. The nuclei of which atoms will decay first? A impossible to know, because radioactive decay is random B impossible to know, unless the age of the material is known C atoms near the centre, because they are surrounded by more atoms D atoms near the surface, because the radiation can escape more easily

50 An atom of the element lithium has a nucleon number of 7 and a proton number of 3. Which diagram represents a neutral atom of lithium?

51. (a) Fig. 10.1 shows an AND gate with two inputs A and B and one output.

State the output when (i) A is high and B is low,

............................................................................................................................ [1] (ii) both A and B are low. ............................................................................................................................ [1]

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(b) An electrical thermometer in a greenhouse gives a low output if the temperature is too low. A humidity sensor in the same greenhouse gives a high output if the humidity in the greenhouse is too high. An alarm sounds when both the temperature is too low and the humidity is too high. (i) Complete the diagram below to show how a NOT gate and an AND gate may be used to provide the required output to the alarm. [2]

(ii) On your diagram, use either ‘high’ or ‘low’ to indicate the level of the inputs and outputs of both gates when the alarm sounds. [2]

52. Fig. 11.1 shows an experiment to test the absorption of β-particles by thin sheets of

aluminium. Ten sheets are available, each 0.5 mm thick.

(a) Describe how the experiment is carried out, stating the readings that should be taken. ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ................................................................................................................................... [4] (b) State the results that you would expect to obtain. ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ................................................................................................................................... [2]

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53. A beam of cathode rays passes through an electric field between two parallel plates. In which direction is the beam deflected? A into the page B out of the page C towards the bottom of the page D towards the top of the page 54. What are the most penetrating and the least penetrating types of radiation?

55. The half-life of a radioactive substance is 5 hours. A sample is tested and found to contain 0.48 g of the substance. How much of the substance was present in the sample 20 hours before the sample was tested? A) 0.03 g B) 0.12 g C) 1.92 g D) 7.68 g 56. The data below relates to the nucleus of a particular neutral atom of nitrogen. proton number Z = 7 nucleon number A = 17 Which row represents the correct number of neutrons and electrons in this atom?

57. When the thermistor in the circuit below is heated, the lamp becomes brighter.

Why does this happen? A The resistance of the lamp decreases. B The resistance of the lamp increases. C The resistance of the thermistor decreases. D The resistance of the thermistor increases.

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58. The diagram shows an experiment to monitor the radiation from a radioactive gas. The counter readings are corrected for background radiation.

The table shows how the counter reading varies with time.

What is the half-life of the gas? A between 20 and 40 seconds B between 40 and 60 seconds C between 60 and 140 seconds D between 140 and 180 seconds 59. Which material is commonly used as a lining for a box for storing radioactive samples? A aluminium B copper C lead D uranium

60. Fig. 10.1 shows a circuit for a warning lamp that comes on when the external light intensity falls below a pre-set level.

(a) On Fig. 10.1, label (i) with the letter X the component that detects the change in external light intensity, (ii) with the letter Y the lamp, (iii) with the letter Z the component that switches the lamp on and off.

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(b) Describe how the circuit works as the external light intensity decreases and the lamp comes on. ......................................................................................................................................... 61. Fig. 11.1 shows the basic design of the tube of a cathode ray oscilloscope (CRO).

(a) On Fig. 11.1, write the names of parts A, B, C and D in the boxes provided. [2] (b) State the function of: part A, .............................................................................................................................. ......................................................................................................................................... part B. .............................................................................................................................. ................................................................................................................................... [2] (c) A varying p.d. from a 12 V supply is connected to a CRO, so that the waveform of the supply is shown on the screen. To which of the components in Fig. 11.1 (i) is the 12 V supply connected, ............................................................................................................................ [1] (ii) is the time-base connected? ............................................................................................................................ [1]

63. (a) In the space below, draw the symbol for a NOR gate. (b) Describe the action of a NOR gate in terms of its inputs and output. ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ................................................................................................................................... [2] (c) A chemical process requires heating at low pressure to work correctly. When the heater is working, the output of a temperature sensor is high. When the pressure is low enough, a pressure sensor has a low output. Both outputs are fed into a NOR gate. A high output from the gate switches on an indicator lamp. (i) Explain why the indicator lamp is off when the process is working correctly. ................................................................................................................................. .................................................................................................................................

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............................................................................................................................ [1] (ii) State whether the lamp is on or off in the following situations. 1. The pressure is low enough, but the heater stops working. ............................. 2. The heater is working, but the pressure rises too high. .............................. [2]

64. (a) Chlorine has two isotopes, one of nucleon number 35 and one of nucleon number 37. The proton number of chlorine is 17. Table 11.1 refers to neutral atoms of chlorine. Complete Table 11.1.

(b) Some isotopes are radioactive. State the three types of radiation that may be emitted from radioactive isotopes. 1. ....................................................... 2. ....................................................... 3. ....................................................... [1] (c) (i) State one practical use of a radioactive isotope. ................................................................................................................................. ............................................................................................................................ [1] (ii) Outline how it is used. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ................................................................................................................................. ............................................................................................................................ [1]

65. A beam of ionising radiation, containing α -particles,β -particles and γ -rays, is travelling left to

right across the page. A magnetic field acts perpendicularly into the page. (a) In the table below, tick the boxes that describe the deflection of each of the types of radiation as it passes through the magnetic field. One line has been completed, to help you.

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(b) An electric field is now applied, in the same region as the magnetic field and at the same time as the magnetic field. What is the direction of the electric field in order to cancel out the deflection of the

α -particles?

................................................................................................................................... [2]

66. In a cathode-ray tube, a hot tungsten cathode releases particles by thermionic emission. What are these particles? A α-particles B electrons C protons D tungsten atoms 67. The diagram shows a cathode-ray tube. A student wants the cathode rays to make a spot at P on the screen. Which parts of the cathode-ray tube should be positive? A anode and top Y plate B anode and bottom Y plate C cathode and top Y plate D cathode and bottom Y plate

68. A radioactive nucleus contains 138 neutrons. The nucleus emits an α-particle. How many neutrons are in the nucleus after it has emitted the α-particle?

A) 134 B) 136 C) 138 D) 139 69. The graph shows the decay curve for one particular radioactive nuclide.

What is the half-life of this nuclide? A) 1.0 day B) 1.5 days C) 2.0 days D) 2.5 days