· web viewextra information eg wave speed increases faster between0-40 m than between 100-140...

M1. (a) b1

c1

correct order only

(b) mirror opposite road junction1

mirror facing correct way, angle correctjudged by eye

1[4]

M2. (a) (i) oscillation1

direction1

correct order only

(ii) sound1

(b) 1.6allow 1 mark for correctsubstitution into correct equation ie 2 x 0.8

2

(c) as the wavelength increases so does the wave speed1

extra information eg wave speed increases faster between0-40 m than between 100-140 m

or

not in proportion1

[7]

m3

(i) X-rays

infra red (rays)

radio (waves)all three in correct orderallow 1 mark for 1 correct

2

(ii) to kill cancer cells1

(iii) energy1

[4]

M4. (a) C (only)1

(b) A (only)1

[2]

M5. (a) (i) shorter than

1

(ii) increase slightly1

(b) (i) go up in the same ratioor (directly) proportional or as speed (of the tennis ball) increases so does the(difference in) frequency

accept as one goes up, so does the otheraccept positive correlation

1

(ii) 20 (m/s)allow 1 mark for showing correct method on graph(ie horizontal or vertical line anywhere on graph)if indicated by a cross, must be ± half square of correct value)

2

(iii) frequency and speed are both continuous variables1

[6]

M6. (a) reflection at the mirror of ray from tip of real puppy’s ear to real puppy’s eye (1)may be drawn freehand

accurate (1)ruler must have been used and the reflected ray is an extension of the straight line from point virtual ear however the virtual part of the line need not be shown

arrow to show correct direction (1)only one arrow needs to be shown but there must be no contradictionexample of (3) mark response

3

(b) flataccept ‘it’s not curved/bent’accept ‘it’s straight’

1[4]

M7. (a) the normal1

(b) v1

(c) any one from:

• light has moved from glass to air / from air to glassaccept light has changed medium

• speed of light has changedbeware of contradictions for this marking point eg light has moved from glass to air and slowed down gets zero

• angle of incidence is less than the critical angleor (angle) i < (angle) c or (angle) y is less than the critical angle

• change in density (of medium)eg glass is more (optically) dense than air

1

(d) (i) ratio of v to y does not give the same answer (in every case)

or value of v doubles value of y does not double1

or increments for v are the same but increments for y are not the sameallow for 1 mark a calculation but no conclusioneg 30 → 60 19 → 35 (38)

1

(ii) as (angle) v increases, angle y increasesaccept as the angle of incidence increases, the angle of refraction increasesor there is a (strong) positive(non-linear) relationship between the variablesor ratio of sines is constantdo not accept angle y is not directly proportional to angle v

1

(iii) no evidence outside this rangeOWTTE

or when angle y is greater than the critical angle total internalreflection occurs

1[7]

M8. (a) (i) a horizontal distance indicated and labelledgains 1 mark

buthorizontal distance indicated between identical points onadjacent waves (to within 3-4mm) and labelled

gains 2 marks2

(ii) peak ↔ trough indicated*gains 1 mark

butpeak / trough ↔ mean indicated*

(* to within 1-2mm either end)gains 2 marks(allow 1 mark if both lines unlabelled or 2 marks if both lines accurately drawn and unlabelled)

2

(b) • 1.5

• hertz / Hz or (waves / cycles) per secondfor 1 mark each(do not allow wavelength / hertz per second)

2[6]

M9. (a) (i) more turns or waves per secondaccept spinning or turning or faster

1

(ii) less time spent cutting field linesaccept shorter time in field or when the frequency increases (the wavelength decreases)

1

(iii) more energy givenaccept more KE put inaccept a higher voltage produceddo not credit more power

1

(b) more coils1

more powerful magnetsaccept put in better bearingsdo not credit reduce friction or add soft iron core

1[5]

M10. (a) amplitude marked as approximately half a wave heightgreat precision is not required

1

wavelength marked as a trough to trough distance or a peak to peak distance

accept an equivalent repeat distance anywhere on the wave1

(b) the number of waves each secondaccept cycles per second accept 25 waves pass each second

1

(c) any pair from

microwave cooking or communication or mobile phone

radio communication or entertainment

infra-red cooking or heating or remote control or security or night sights or thermal imaging

accept sensible specific uses2

[5]

M11. (a) changes the sound wave(s)

to a varying or changing (electric) potential difference or p.d. or voltageor current or to an irregular alternating current or a.c. or transferssound energy to electrical energy (1) mark is vibrations or pulses or ofsound or in air become electrical waves

do not credit just ‘to electricity’ or ‘to a.c’2

(b) (i) decrease or reduce the amplitudeaccept less amplitude nothing else added

1

(ii) increase the frequency or decreasewavelength

accept higher frequency nothing else added1

[4]

M12. (i) speed = frequency × wavelengthaccept the equation rearrangedaccept v or s = f × λdo not allow w for wavelengthdo not accept

unless subsequent calculation correct1

(ii) 330 (m)allow 1 mark for

λ =

or 300 000 000 = 909 000 × λor answer of 330000(m) or 330033(m)

2[3]

M13. (i) all electromagnetic waves travel at the same speed through a vacuum, (soassume same speed in air)

accept ‘all parts of spectrum’ for electromagnetic waves1

(ii) 1500 (m)allow 1 mark for correct transformation and substitutionallow 1 mark for using 200 000 Hzanswers 1 500 000 = 1 mark

2

(iii) line drawn at correct positionanywhere between 1000 and next section (10 000)accept their value for (a)(ii) drawn inthe correct position

1[4]

M14. (i) 0.51

(ii) wave speed = frequency wavelengthaccept v = f × λaccept s for vaccept m/s = Hz maccept

providing subsequent method correct1

(iii) 15.2 kmboth numerical answer and unit are required for both marksnumerical answer and unit must be consistentallow 1 mark for 15.2 with incorrect or no unitallow 2 marks for an answer of 1.52 km if the answer to (b)(i) was given as 5r 1 mark for correct transformation

or 1 mark for correct use of speed = distance/timeunit on its own gains no credit

2[4]

M15. (i) speed = frequency × wavelengthaccept the equation rearrangedaccept v or s = f × λdo not allow w for wavelengthdo not accept

unless subsequent calculation correct1

(ii) 330 (m)allow 1 mark for

λ =

or 300 000 000 = 909 000 × λor answer of 330000(m) or 330033(m)

2[3]

M16. (a) (i) 400 000 000orcorrect equivalent

allow 1 mark for correct transformation and substitution (of 75)answer 4 000 000 gains 1 mark only

2

(b) (i) any mention of alpha, beta, gamma waves scores 0 marks

emit / uses / transmit / receive microwavesaccept radiation for microwaves throughoutignore radio waves

1

some microwave / energy absorbed by / enters the bodyecf for their given electromagnetic wavedo not accept goes through the body

1

raises temperature of (body) cells / tissue / wateraccept reference to water molecules vibrating fasteraccept it could cause mutation / harm / kill cellsdo not accept answers in terms of ionisationignore references to cancer

1

(ii) any two from:

• research (may be) biasedor may have been misled in the pastaccept not independentor may be lying

• some research suggests a link

• long-term effect not proven / studiedaccept not studied for long enough

• residents may not have seen the research2

[7]

M17. (a) (i) any two from:

• travel at the same speed (through a vacuum)accept travel at the speed of lightaccept air for vacuum

• can travel through a vacuum / space

do not accept air for vacuum

• transfer energy

• can be reflected

• can be refracted

• can be diffracted

• can be absorbed

• can be transmitted

• transverseaccept any other property common to electromagnetic wavesaccept travel at the same speed through a vacuum for both marksdo not accept both radiated from the Sun

2

(ii) infra redboth required for the mark

radio(waves)accept IR for infra red

1

(b) 2 400 000 000correct transformation and substitution gains 1 mark

ie or an answer of 24 000 000 gains 1 markeither 2 400 000 kHzor 2 400 MHz scores 3 marks but the symbol only scores the 3rd mark if it is correct in every detail

2

hertzaccept Hzdo not accept hz

1

(c) (i) presented (scientific) evidence / data

do an experiment / investigation is insufficient1

(ii) to find out if there is a hazard (or not)accept to find out if it is safeaccept not enough evidence to make a decisionnot enough evidence is insufficient

1[8]

E3. (i) Most candidates knew that radio waves have the longest wavelength, but many put X-rays and infra red rays the wrong way round.

(ii) Most candidates realised that a use of gamma rays is to kill cancer cells.

(iii) Only about 50% of the candidates knew that electromagnetic waves move energy from one place to another.

E4. Most were able to identify the wave patterns with the smallest amplitude and with the lowest frequency.

E5. (a) (i) The majority of candidates picked up the clue from the diagram, and correctly stated that the wavelength of the microwaves reflected from the ball are shorter than those from the speed gun.

(ii) The majority of candidates identified that the temperature of the ball will increase slightly.

(b) (i) Some candidates appeared not to understand what was meant by the word ‘pattern’. Thus they were offering answers such as ‘It goes straight up’. Most candidates did score a mark here, even if they stated that the frequency was increasing rather than the difference in frequency increasing.

(ii) It was pleasing to see that most candidates were able to obtain the correct answer of 20m/s. The most common mistake was to read the scale on the y axis incorrectly: many candidates thought that they needed to count two little squares up from the 3000Hz line to reach 3200Hz. They therefore reached a figure of more than 20m/s. Those candidates who heeded the advice in the rubric to ‘show clearly on the graph how you obtain your answer’ were able to score one mark if they showed a suitable method on the graph, even if they subsequently arrived at the wrong answer.

(iii) The majority of candidates selected the correct answer.

E6. (a) Less than a third of candidates gained full marks. Many either gained no marks or made no attempt at the question.

(b) Less than half the candidates could give a correct meaning to the term ‘plane’ in the context of a plane mirror. Some suggested it means a mirror without ornamentation.

E7. (a) Nearly all candidates could name the normal.

(b) Nearly two-thirds of candidates recognised that, on the diagram, v is the angle of refraction.

(c) Just over two thirds of candidates knew why refraction has taken place.

(d) (i) Candidates generally secured two marks by comparing the values for 30° and 60° or for 40° and 80°. Credit was also given for other mathematically correct responses such as, ‘the angles are not directly proportional because v ÷ y is different for every pair. For example, it’s 1.58 for the first pair and 1.95 for the final pair’.

(ii) Nearly two thirds of the candidates were able to offer a correct conclusion.

(iii) Just over half of the candidates were able to explain that the conclusion is only valid in the range 30° to 80° because there is no evidence outside this range.

E9. This was one of the more discriminating questions. The relationship between frequency and wavelength may be known but many could not apply it to the situation given. It would seem that the link of amplitude to energy was only appreciated in the context of sound, as most answers were given in terms of loudness. Many candidates did not know how to adapt a generator to increase its output. A longer handle was a favourite suggestion.

E10. Part (a) was well answered but with a few peak-to-trough amplitudes. Part (b) was well answered.

E11. Most candidates appreciated that microphones transform sound energy to electrical energy, but failed to qualify the answer to gain the second mark. Many knew how to change the loudness and the pitch of a sound.

E12. This question gave a full range of marks and it was quite well answered, although 909 kHz was often not converted to hertz.

E13. In part (i) few candidates realised that since both light and radio waves travel at the same speed in a vacuum they are likely to travel at the same speed through air. In part (ii) many candidates calculated the correct answer. The most common error was not to convert kHz to Hz. Part (iii) was not attempt by a significant number of candidates.

E14. Most candidates were able to attempt this question although many could not give the correct number of waves produced in one second or give the correct wave equation.

E15. This question gave a full range of marks and it was quite well answered, although 909 kHz was often not converted to hertz.

E16. In part (a)(i) a significant number of candidates divided by 75cm arriving at an answer of 4,000,000.

Part (b)(i) produced a wide range of answers; however few candidates scored all three marks. Many candidates scored two marks for the idea of ‘microwaves damaging cells’. Most candidates scored at least one mark in part (b)(ii) with almost half scoring full credit. The idea that research could be biased and the need to present the evidence was well known.

E17. (a) (i) It appeared that the term .properties. was not understood by many candidates, and answers giving uses of the waves were more frequently seen. Candidates should be aware that they do not generally gain credit for repeating information which they have been given in the question, so saying that both waves were electromagnetic or that both could be used for communications did not score any credit.

(ii) This question was correctly answered by just under three quarters of candidates, although some candidates gave .visible light and microwaves. as an answer, failing to realise that the question had already referred to these waves.

(b) Although a large number of candidates were able to transform the equation and

substitute values, the majority failed to convert the wavelength from centimetres. The majority of candidates either did not read that they also had to give the unit, or perhaps did not know what the unit was, but those who gave the unit usually did so correctly.

(c) (i) Many candidates seemed to have the correct idea but failed to express themselves correctly. A common incorrect answer was to suggest that the politician should carry out an experiment.

(ii) A surprisingly large number of answers indicated that candidates had read the question as asking why there was ‘no need for further research’. Other answers included terms such as ‘bias’, ‘valid’ and ‘accurate’ that did not answer the question.

· web viewextra information eg wave speed increases faster between0-40 m than between 100-140...

Documents